Skin covering. The basis of the skin in some breeds of dogs is moderately thick and relatively rough, in others it is thin, soft and elastic. The coat is generally thick, but extremely variable in length, hardness, smoothness or curlyness.
The hair is most densely located on the back, as well as on the dorso-lateral surface of the limbs, where the base of the skin itself is thicker than on the abdomen and medial surface of the limbs.
On the lips, as well as above the eyes, often in the intermaxillary region and on ganaches, long sinus hairs are developed with increased sensitivity in the roots.
In some breeds, the tail hair reaches a considerable length (fluffy tail). Hair is absent on the nasal planum. Special figures of hair streams are observed on the neck, front and lower surfaces of the chest, on the upper links of the limbs.
Hair in dogs are connected in groups of 4-8 pieces in such a way that their bulbs in the depths of the cover stand one by one one next to the other, and towards the surface, that is, towards the epidermis, they come closer and appear outward from one common hair funnel. In this case, very often one of the hairs of the group turns out to be the most strongly developed: this is the main hair of the group, and the rest, weaker, are side hairs.
Crumbs and claw. Dogs have: 1) carpal, 2) metacarpal, metatarsal and 3) digital crumbs.
1. Carpal crumb - pulvinus carpalis (Fig. 244-a) - lies in the form of a small skin elevation on the volar surface of the wrist near the accessory bone. It does not participate in support, but represents a rudiment that allows us to assert that the animal in its past was plantigrade, when this crumb also served as a support on the ground.
2. Metacarpal crumb - pulvinus metacarpalis (b) - the most significant in size, approximately heart-shaped. It is located in the region of the distal end of the metacarpal bones and the beginning of the first phalanges of the fingers. Its base is turned towards the wrist, and the top is slightly extended between the fourth and second finger crumbs. When attacked, it is mainly the joints of the first phalanges that rest against it. The same crumb is present on the pelvic limbs - metatarsal crumb - pulvinus metatarsalis. The metacarpal crumb is connected with the first phalanges of the 3rd and 4th fingers with a special suspension ligament.
3. Finger crumbs - pulvini digitales (c) - are present on each finger in the region of the 2nd and beginning of the 3rd phalanx. It is strongly advanced towards the claw from the plantar side.
On the claw - unguiculus - allocate:
1) nail roller with nail groove, 2) nail wall with rim and 3) nail sole.
1. The claw roller is the area of ​​transition of the skin of the finger into the claw. Here, in addition to the epidermis and the base of the skin, there is also a subcutaneous layer (hence the base of the skin is folded into a bone claw groove). The claw roller covers the base of the claw and passes into this latter towards the digital crumb. The epidermis from the region of transition to the gutter gives a thin stratum corneum to the horny wall of the claw and dresses the latter from the surface in the form of glaze. From the roller, the epidermis and the base of the skin are bent into the bone groove of the 3rd phalanx and form the ungual groove. It is especially deep in cats. From the depths of the groove, the base of the skin with its epidermis appears on the ungual wall and turns here on the dorsal surface into the base of the skin of the corolla (j), entering into the composition of the ungual wall.
2. The nail wall with the rim (d) is one whole, located on the dorsal (corolla) and lateral surfaces of the claw, and the rim appears from the depths of the ungual groove.
3. Claw sole (e) is narrow and localized on the plantar side of the claw.
The skin layers are distributed as usual: 1) the subcutaneous layer, 2) the base of the skin and 3) the epidermis.
1. The subcutaneous layer exists only at the site of the transition of the skin to the claw and does not represent anything special in its structure.
2. The base of the skin of the claw is firmly fused everywhere with the periosteum of the 3rd phalanx. On separate parts of the claw, it is built as follows:
a) The base of the corolla skin - corium coronae (k) - originates in a wide strip in the depths of the ungual groove, then, gradually narrowing, thickens on the convex dorsal surface of the 3rd phalanx and stands out here in the form of a significant hook-shaped appendage, firmly connected to the periosteum of the phalanx . All this thickening serves as the basis for the corolla skin.
Papillae based on the skin of the corolla are developed only in the depth of the trough, the rest of its surface is smooth.
b) The basis of the skin of the wall - corium parietale (l) - is already divided by the basis of the skin of the corolla passing along the back into the right and left sections. The areas of the base of the skin of the wall are insignificant in terms of the occupied area, they are located on the sides from the roller-like corolla to the plantar surface. Parallel leaflets of the papillary layer stretch in gentle arcs along the lateral surfaces of the 3rd phalanx.
c) The base of the skin of the sole - corium soleare - is quite massive and bears papillae, directed downwards with their tops.

3. The producing layer of the epidermis of the claw is located on the papillae and lamellae of the base of the skin of the claw. It produces the stratum corneum, which serves as the horny capsule, or horny shoe, of the claw. On the claw, the horny capsule breaks up into: a) the horny wall and b) the horny sole of the claw.
a) The horny wall of the claw - paries cornea unguiculi - is a complex formation. It covers the claw from the back and sides and is a merger into one whole of the stratum corneum of the wall itself - stratum parietale - with the coronal stratum corneum - stratum coronarium.
The coronal stratum corneum (d) is the densest and most durable corneal part of the capsule. It begins with a wide root in the depths of the groove, towards the back of the claw, gradually narrowing, thickening and ending in a curved point, hanging at the top beyond the claw sole.
The stratum corneum of the wall (e) is less dense. It merges without borders with the coronal layer, and with free edges adjoins the horny sole from the sides and even hangs down somewhat on the sides, partially covering the sole.
b) The horny sole of the claw - solea cornea unguiculi (e) - is relatively narrow, consists of a tubular loose horn and develops from the producing layer lying on the papillae of the base of the skin of the sole.
Thus, a significant difference between the claw of dogs and the claw of a more primitive structure (in reptiles) is the presence of a nail rim as an additive, which grows entirely towards the claw wall and gives it greater strength. This should be especially noted, since we have seen that in ungulates this process deepens even further, giving rise to a coronal stratum corneum over the entire width of the wall.
In dogs, the claw can touch the soil with its tip and therefore becomes dull with age.
In cats, the claw is almost completely hidden in the fold of the back of the finger, so that the digital cushion protrudes even more forward. The claw is extended only in case of need, when it must be used as a weapon of attack and self-defense. It is strongly curved, sharp at the apex, its root is very deeply pushed into the claw groove, and therefore very strong. Powered by the musculature of the fingers, it is able to produce great destruction on the body of prey or the enemy.
The claw is protected from abrasion by special elastic ligaments; they go along the back side from the 2nd phalanx of the finger to the 3rd (k). The more developed these ligaments (cat), the deeper the claw, when the muscles are at rest, hides in the integumentary depression of the second phalanx.
Skin glands. Sebaceous glands exist in all breeds of dogs, but their density on the body is not the same: in short-haired animals, with coarse outer hair, they are more developed, and in dogs with long and delicate hair, they are weaker. Generally speaking, they are thicker on the lips, dorsal side of the trunk, and ventral chest.
Sweat glands, obviously, are underdeveloped even in embryonic life. They stand out more clearly on the skin of dogs with long, delicate, sparse hair.
In cats, the sweat glands are even less developed.
Mammary gland. Dogs (Fig. 237-B), like pigs, tend to have multiple udders with five, less often four mounds on each side. On the skin of the nipples there are rare delicate hairs, sebaceous and sweat glands. At the top of the nipple open (varying in the amount of 6-12) nipple canals. The passages in the nipple during lactation slightly expand, forming a semblance of a tank.

LEATHER

Skin - cutis - epithelial-connective tissue organ. Performs a number of important functions for the life of the body: protects the body from external influences; performs through a variety of nerve endings (exteroreceptors) the role of the receptor link of the skin analyzer of the external environment (tactile, pain, temperature sensitivity); through many sweat and sebaceous glands, it secretes a number of metabolic products; through the mouth of the hair follicles, skin glands, the surface of the skin can absorb a small amount of solutions. The blood vessels of the skin can contain up to 10% of the blood of the animal body. Constriction and dilation of blood vessels are essential in the regulation of body temperature. The skin contains provitamins, under the influence of ultraviolet light, vitamin D is formed.

The skin and derivatives of the skin are parts of the whole organism of the animal. Their appearance, texture, temperature, sensitivity reflect the state of metabolism and functions of a number of organ systems,

In the skin covered with hair, the following layers are distinguished (Fig. 122): 1) cuticle (epidermis) - epidermis from stratified squamous keratinized epithelium; 2) the basis of the skin, the dermis (skin itself) - dermis (corium); 3) subcutaneous base (subcutaneous layer) - tela sub-cutanea (subcutis) in the form of loose connective and adipose tissue.

The epidermis of hairy skin is 20-60 microns thick. It has three layers: a) basal, producing a layer of cylindrical, oval cells capable of intensive reproduction, and melanocyte cells that form a pigment - dark melanin; b) a layer of rounded and flattened cells in which keratin accumulates; c) keratinized flat cells, scales. The keratinized cells are pinched off, and thus dirt, microorganisms, and dyes are removed from the surface of the skin.

Rice. 122. Structure of the hairy skin of cattle, horses, coarse-wooled sheep

There are no blood vessels in the epidermis.

The epidermis is connected to the skin's own layer by a basement membrane, through which the exchange of substances between the epidermis and the subepidermal layer takes place.

At the heart of the skin - the dermis of cattle, horses, coarse-haired sheep, dogs, two layers are distinguished: a) pilar hair-containing - sir. pflare and b) mesh - str. reticulare (see Fig. 122, I).

The pilar layer is located from the epidermis to a conditional line passing under the hair follicles and sweat glands. In this layer there are sebaceous and sweat glands, hair roots in hair follicles, smooth muscles-hair lifters - mm. arrectores pilorum, many blood and lymphatic vessels and nerve endings. In the pilar layer under the epidermis there is a papillary layer - stratum papillare with a thickness of 200-350 microns. The boundary of this sublayer passes at the level of the sebaceous glands.

The mesh layer of the base of the skin consists of a plexus of collagen and a small amount of elastic fibers, blood vessels and nerve fibers passing into the pilar layer. The main layers of the skin are visible macroscopically. Between the hair shafts, the surface of the skin is visible, covered with the epidermis, colored in black and gray by melanin and in yellowish shades by phelanin pigments. The uneven surface of the epidermis has a certain pattern - "measure". On a skin incision under the epidermis, a pilar layer with hair roots is visible and under it is a mesh layer of dense whitish connective tissue, deeper is loose whitish connective tissue of the third layer of the skin - subcutaneous. The subcutaneous layer is attached to the superficial fascia that covers the body of the animal.

If the subepidermis layer is damaged, abrasions are formed, in place of which hair growth is preserved; within a few days, the epidermis is restored due to the regeneration of the epithelium from the wall of the hair follicles. When the entire pilar layer is destroyed, hair growth stops, flat granulating ulcers appear, and the remaining mesh layer prevents the edges of the ulcer from shrinking. In surgery, for free transplantation, subepidermal and pilar skin flaps are used, corresponding in structure to the layers mentioned above.

Skin with hair and subcutaneous tissue removed from the body of an animal is called a skin.

The thickness of the skin is not the same in different areas of the body of animals of different species, breeds, age and sex.

Skin thickness can be determined on a live animal. Half the thickness of the skin fold, collected together with subcutaneous tissue, is equal to the thickness of three layers of skin. Exact skin thickness is determined on a piece of excised skin. In pigs, it is impossible to collect a fold of skin on a significant part of the body, the thickness of the skin is determined by ultrasound.

Blood vessels in the skin form 4 plexuses: large-loop in the subcutaneous layer, dermis, at the base of the pilar layer and at the level of the sebaceous glands in the subepidermis sublayer, where capillary loops approach the basement membrane of the epidermis.

Lymphatic vessels are more often located in the form of two main plexuses: in the subepidermis (papillary) sublayer and on the border with the subcutaneous tissue.

The skin has the richest receptor field of the skin analyzer.

Nerve fibers form plexuses in the subcutaneous tissue, then inside the pilar layer and under the epidermis. Nerve endings reach the basal layer of the epidermis. Many nerve fibers branch out in the walls of the hair follicles. Encapsulated nerve endings in hairy skin are rare.

So slow. Growing mainly fat islands, to a lesser extent - the connective tissue stroma and even less - the system of ducts of the gland. With the onset of puberty, the connective tissue, glandular epithelium and udder vascular network begin to develop intensively. The connective tissue stroma overtakes the glandular parenchyma in development, and only during pregnancy does the epithelial tissue grow faster than the connective tissue, it differentiates into all elements of the glandular parenchyma, and by the end of pregnancy begins to produce colostrum. The highest functional activity of the mammary gland reaches during lactation.

STRUCTURE OF THE SKIN

Skin - cutis - a strong, elastic membrane covering the animal's body, in the area of ​​\u200b\u200bnatural openings passing into the mucous membrane. The mass of skin in most adult animals is within 5-7% (without fleece in sheep) of body weight, which is 20-40 kg in cattle, 1.5-2.5 in sheep, 7-10 in pigs, a horse is 8-20 kg. In newborn animals, the skin is relatively heavier: in calves 11-12%, in piglets 12-18%. The thickness of the skin varies in animals of different species and in different parts of the body: in cattle, the skin is dense, of medium thickness (3-6 mm), in sheep it is thin (0.7-2 mm), in pigs it is rough and thick (with under -

Changed with the skin DEMO fiber VERSION of5 CAD-7 -KAScm), PDF horses -Editor (http://www1-7 mm. Usually .cadkas.com) have thicker skin located on the dorsal surface of the neck (nape), back, croup; medium thickness - on the sides; the thinnest - on the belly and medial surfaces of the limbs, especially in the region of the inguinal fold. There are differences in the thickness of the skin associated with sex and behavioral characteristics: in boars, wild boars and goats, the thickest skin is on the ventral part of the neck and presternal region, the so-called shield.

The skin consists of the epidermis, dermis and subcutaneous tissue (Fig. 82). Epidermis - epidermis (1) - the surface layer of the skin, which she

comes into contact with the environment. Its thickness is 30-60 microns in cattle, 10-30 microns in sheep, and 40-50 microns in horses. It is formed by stratified squamous keratinized epithelium. In areas of the body not covered with hair, it consists of 5 layers: basal, spiny, granular, shiny and horny (see section three). The basal layer performs a cambial function due to the multiplication of stem cells that make up its composition. Between the cells of the epithelium - epidermocytes lie process pigment cells - melanocytes, which produce and accumulate pigments. They determine the color of the skin and perform the function of protecting against excess ultraviolet rays.

The protective properties of the epidermis are determined by the thickness and condition of its stratum corneum. An increase in temperature, exposure to alkalis, acids, organic solvents increases the permeability of the epidermis. It is replenished by cells coming from the underlying layers, which

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Vrakin V.F., Sidorova M.V.	MORPHOLOGY OF FARM ANIMALS

which, as they come to the surface of the skin, are keratinized. The stimulus for keratinization is the difficulty in nutrition and changes in substances in cells as they move away from the basement membrane (epithelial nutrition is diffuse). At the same time, keratinoid proteins accumulate in the cells, the granules of which are visible in the upper rows of the epidermocytes of the spinous layer. In the cells of the granular layer, granules of keratohyalin fill the entire cytoplasm, the cells flatten and, as it were, flatten out. In the process of cell death, the grains of keratohyalin merge and undergo chemical transformations - eleidin is formed, which fills the flat wide cells of the shiny layer.

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Rice. 82. The structure of the skin (A- without hair, B - with hair):

I - epidermis; II dermis; III - subcutaneous tissue; 1-stratum corneum; 2-shiny layer; 3- granular layer; 4 - prickly layer; 5 - basal layer - dermis; 6 - papillary layer; 7 - mesh layer; 8-output duct and 9 - terminal section of the sweat gland; 10 - blood vessel; eleven

lymphatic vessel; 12 - 14 - accumulations of fat cells; 15 - hair shaft; 16 - hair root; 17 - hair follicle; 18 - nerve; 19- nerve endings; 20 - changing hair. bundles of collagen fibers.

Keratinization is accompanied by water loss. Mature eleidin becomes keratin - a protein rich in sulfur, very resistant to various influences. The cells by this time die off and look like horny scales - flat spread over the surface so that the area of ​​one scale is equal to the area occupied by 5-15 basal cells. Scales

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Vrakin V.F., Sidorova M.V.	MORPHOLOGY OF FARM ANIMALS

contain keratin, air bubbles, neutral fats are found between them. When the connection between cells is disrupted (degradation of desmosomes), the scales are sloughed off. The stratum corneum consists of many rows of scales. In areas subjected to constant friction, pressure and other mechanical influences, the stratum corneum thickens significantly, which can be seen in the structure of the crumbs. Normally, the wear and desquamation of the epithelium from the surface of the stratum corneum is replenished by growing and differentiating cells.

IN In areas of skin covered with hair, the epidermis is thinner and consists of basal, spiny, granular, and stratum corneum.

Derma - derma (II), or the skin itself, underlies the epidermis, delimited from it by a basement membrane, formed by connective tissue and consists of papillary and reticular layers.

IN in areas of skin devoid of hair, the boundary between the epidermis and dermis is uneven. The ingrowth of the epidermis deep into the dermis is called scallops. The dermis is wedged into the epidermis in the form of papillae, which is why the layer adjacent to the epidermis is called papillary. In the skin with hair, the scallops and papillae are weakly expressed. This layer varies greatly in thickness in animals of different species: from 100 microns in a pig to 2 mm in cattle and is in a cow 18-20%, in a pig 3%, in a horse 30-35% of the thickness of the dermis. The papillary layer is characterized by the fact that it consists of loose connective tissue with a large number of various cellular elements (fibroblasts).

Changed with thests DEMO, fibrocytes VERSION, histiocytes of CAD-KAS PDF, mastocytes -Editor (http://www, pigment .cadkas cells .com).etc.), blood-

nasal and lymphatic capillaries, nerves and nerve endings.

There are no clear boundaries between the layers of the dermis. The division is based on the fact that the reticular layer, unlike the papillary layer, is formed by a dense, unformed connective tissue. This tissue contains a large amount of collagen and much less elastic fibers. Among the connective tissue proteins of this layer, 98% are collagen. Depending on the size, density, direction and nature of the interlacing of bundles of collagen fibers, several types of tie are distinguished. The strength of the mesh layer of the dermis, its mechanical properties depend on the nature of the tie. In most animals, this layer is the main one in thickness.

Subcutaneous base (fiber)- tela subcutanea (III) - formed by loose connective tissue. Connects the skin to the superficial fascia and subcutaneous musculature. In the subcutaneous tissue, accumulation of adipose tissue is often observed, especially during fattening. Most often, fat is deposited in the neck, shoulder, withers, in a narrow strip along the spine, on the sacrum, on the sides, at the rear edge of the chest, in the groin, around the anus. In a pig, a large amount of fat, bacon, grows in the subcutaneous tissue throughout the body. In a camel, fat is deposited in the humps, in fat-tailed sheep - at the root of the tail and on the buttocks, forming a fat tail. The subcutaneous base provides the skin with mobility, is a fat depot. Thanks to the accumulation of fat, the skin takes part in thermoregulation.

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Vrakin V.F., Sidorova M.V.	MORPHOLOGY OF FARM ANIMALS

Vascularization and innervation of the skin. The skin is richly supplied with vessels

mi, which form several plexuses in it: under the epidermis, between the layers of the dermis, on the border with the subcutaneous base and in the base itself. Both between the plexuses and inside there are numerous anastomoses involved in the redistribution of blood and thermoregulation.

The skin is innervated by both the nerves of the somatic and autonomic nervous systems. They form plexuses in the subcutaneous tissue, in the dermis and under the epidermis. The sensory nerves of the somatic nervous system form numerous and diverse sensory nerve endings in the skin, both free and non-free. Free nerve endings branch predominantly in the epidermis. In the dermis there are free rectilinear, glomerular, dendritic and non-free (Vatera

Pacini, Krause, Meissner) nerve endings. The skin of the eyelids, lips, proboscis, nasolabial mirror, ears, abdominal wall, finger crumbs, udder, genitals is especially rich in nerve endings. The autonomic nervous system innervates the vessels, glands, muscles, hair lifters.

hairline- a feature of the skin of mammals. It is formed by derivatives of the epidermis - hair and protects the skin from moisture, mechanical, electrical and other influences. In different parts of the body and in animals of different genera, the hairline varies greatly in composition, density, and length of hair. Sheep have thin skin covered with a long, thick

Changed with the new DEMO hairline VERSION of CAD-KAS. The PDFpigs-EditorSkin (http://wwwthick.cadkas with rare .com) located .

coarse hair, which in certain areas become bristles. Cattle have a relatively uniform, medium-density hairline.

According to the features of the structure and function, tactile, long and covering hair are distinguished. Tactile (sinuose, vibrissae) hair is thick sensitive, their root is surrounded by blood vessels and nerve endings. They are located on the muzzle near the mouth and eyes. They perform a receptor function. Long hair grows in certain parts of the body: on the tail, on the bangs and brushes, on the mane of horses, on the sides of the body on yaks. They perform a protective function. The bulk of the hair covering the body is called covering, or integumentary. They are located on the skin in a certain order, forming circular and linear flows. The density of hair in animals of different genera and families is very different. There are animals with underdeveloped hairline. From domestic animals it is a pig. The number of hairs in her is 60-100 per cm2 (of which 3-30 bristles), in cattle 800-1500, in sheep 4000-8000. Among the integumentary hair, bristle, awn, semi-down and down are distinguished. In cattle, pigs and horses, hair grows more or less evenly, in sheep - in groups. In the group there is one guard and several downy (for fine-fleeced - up to 15 pcs.) Hair.

Hair - pilus (Fig. 83) is a hard keratinized elastic thread of a conical, cylindrical, fusiform, lanceolate shape and varying degrees of crimp and color, formed by epithelial cells. In him

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Vrakin V.F., Sidorova M.V.	MORPHOLOGY OF FARM ANIMALS

distinguish between a rod and a root. The hair shaft protrudes above the skin. The root is in the skin and surrounded by the hair follicle. The follicles of the outer hair are laid first and are therefore called primary. Downy hair follicles are laid later and are called secondary. Hair roots in most animals lie in the reticular layer of the dermis. In the pig, the roots of the bristles penetrate the subcutaneous tissue.

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Vrakin V.F., Sidorova M.V.	MORPHOLOGY OF FARM ANIMALS

Rice. 83. Development (A) and structure (B) of a hair (o, b, c, d, e - successive stages of hair development):

1 - epidermis; 2- dermis; 3- hair follicle; 4- hair follicle; 5 - hair papilla; 6- hair root; 7

Hair bag; 8 - external root sheath; 9 - internal root sheath; 10 - hair lifter; eleven

sebaceous gland; 12 - horny substance; 13 - sweat gland; 14 - cuticle; 15 - mink substance; 16 fat

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas cells.; com)17 .- funnel follicle.

The hair follicle has a complex structure. The cavity of the follicle in which the hair root is located is called follicle canal, and its extended upper part is a funnel. The outer part of its wall is formed by connective tissue and is called the hair bag. The bottom of the hair bag is thickened, consists of loose connective tissue penetrated by blood vessels, and protrudes into the depths of the follicle in the form of a hair papilla. The papilla suckers nourish the hair. The inner part of the follicle is epithelial. It consists of two vaginas - external and internal - and passes into a flask-shaped thickening

Hair follicle. External root sheath is a continuation of the germ layer of the epidermis and, gradually thinning, covers the bulb 1-2 layers of cells. Internal root sheath grows from the bulb and reaches only the funnel of the follicle. In cattle, it is present along the entire length of the follicle and passes into the stratum corneum of the epidermis. At the funnel level, the ducts of the sebaceous and apocrine sweat glands open into the canal of the hair follicle. A muscle is woven into the bag of hair (awns and bristles) - hair lifter from smooth muscle tissue.

Cells hair follicle, multiplying, they move up the follicle channel, forming the root, and then the hair shaft. There is an opinion: the larger the bulb, the thicker the growing hair. The cells soon become keratinized and the hair shaft consists of keratinized cells lying in several

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

Vrakin V.F., Sidorova M.V.	MORPHOLOGY OF FARM ANIMALS

concentric layers. The outermost layer of hair cells - the cuticle - is represented by a single-layer squamous epithelium, which looks like scales overlapping each other like tiles. It is chemically neutral and has a protective function. The cuticle cells in each animal species have a characteristic shape, so that it is possible to determine who owns the hair.

Located under the cuticle cortex(bark) hair from several rows of concentrically layered epithelial cells. In the process of differentiation, the cells capture pigment grains from the processes of melanocytes located in the bulb and quickly become keratinized. The keratinized cells of the cortex, like the cuticles, contain solid keratin and remnants of nuclei. The cortical substance of the hair determines its color, strength and elasticity. In the center of the hair is medulla, formed by large, slowly keratinizing cells. Cornification is completed by the transition of the hair root to the shaft. Cells contain soft keratin, air bubbles.

Downy and semi-downy hairs consist only of a cuticle and a cortical substance. The awn contains all three layers.

The change of hair occurs periodically, since the life of the hair is from 50 days to 5 years. The mass change of hair is called molting. It can be juvenile - before puberty and seasonal - usually in spring and autumn. There is also a permanent change of hair (permanent), independent of the annual cycle. This applies primarily to long hair. The change begins with a violation of the nutrition of the hair, then the restructuring of the lumen occurs.

Changed with the DEMO, VERSION after which of the old CAD-KAS hair the PDF loses the Editor (http://www its .cadkas link and from .her com) a new hair grows.

The sebaceous glands - glandulae sebaceae (see Fig. 82-13) - parietal simple alveolar glands with branched terminal sections, secrete according to the holocrine type. They develop from the epithelium of the outer hair sheath of the primary follicle and open into the canal of the hair follicle at the level of its funnel. The sebaceous glands are not associated with down hair follicles. The terminal sections of the gland - the alveoli - do not have a cavity. The wall of the alveolus is lined with a single layer of small poorly differentiated cambial cells. With active division, some of the cells are forced out of the layer deep into the alveoli and enter the path of fatty degeneration. Such cells become larger, droplets of fat accumulate in their cytoplasm. As the cells are pushed out closer to the duct of the gland, an increasingly pronounced fatty degeneration of the cells occurs. Finally, the cells closest to the lumen die, disintegrate, turning into a fatty secret.

The duct of the gland is lined with stratified squamous epithelium and opens into the canal of the hair follicle. The fat secret protects the skin and hair from drying out, maceration, and chemical influences. In sheep, the fat secretion mixes with the secretion of the sweat glands, forming lard, the amount of which can reach 40% of the fleece mass. Zhiropot participates in heat transfer, increases the evaporating surface of the skin and wool, protects the skin from excessive exposure to sunlight and moisture, gives elasticity,

Changed with the DEMO VERSION of CAD-KAS PDF-Editor (http://www.cadkas.com).

1. Epidermis(epidermis) - the first outer layer, a derivative of the ectoderm of the outer germinal leaf. The thickness of the epidermis in various taxonomic groups is 1-4% of the thickness of the skin. The thickness is not the same not only in different taxa, but also in animals of the same taxon living in different ecological conditions. So, for animals living in the tundra, the epidermis is thinner, but the hairline is thicker. And vice versa, thickening of the epidermis and thinning of the hairline for animals living in other zonal belts.

The epidermis of the canine family (fox, arctic fox) is thicker than that of mustelids (ferret, weasel, marten, badger, sable, Siberian weasel, ermine, otter, sea otter).

The thickness of the epidermis is inversely proportional to the amount of hair.

The epidermis is richly innervated, does not have its own blood vessels, therefore its trophism (nutrition) is carried out at the expense of the underlying layer - the dermis.

The epidermis has a number of biological properties.

1) Unequal resorption (suction) capacity.

The following are well absorbed through the epidermis: alcohol, iodine, boric acid, various salts, including mercury salts, etc. However, substances soluble in sebaceous formations (lard, lanolin) penetrate very poorly, so they must be rubbed for a long time so that they penetrate into the depths of the epidermis.

2) The originality of the surface relief.

Each animal (including humans), even identical ones, will have a peculiarity of the relief of the epidermis surface, which is used in forensic veterinary medicine and medical identification. A fingerprint is taken from the nasolabial mirror and a fingerprint map is made. The epidermis has a folded relief, which is found at the level of a magnifying glass, and at a magnification of 5-7 times, ridges and troughs are visible on it.

3) Eliminative ability.

The ability to remove foreign parts from a deeper layer is used in skin regeneration.

Epidermis, or cuticle - in mammals, it is formed by a stratified squamous, slightly keratinized epithelium, almost a cellular formation, where cells prevail over a small amount of intercellular substance. Cells are distributed in several layers. Of greatest interest are the cells of the inner layer, which border the dermis - 1) basal layer. The cells of this layer are constantly multiplying and due to this, all subsequent layers of the epidermis are renewed. The cells of the basal layer are heterogeneous.

In addition to basal epidermocytes,

3 more types of cells with special functional purposes have been identified:

Langerhans cells (1868) are involved in immune reactions of the skin;

Merkel cells (1917) are sensitive, functions are being studied;

Pigment cells - melanocytes containing melanosome organelles that produce pigment melanin. Albinos do not have pigment.

2) Spiny layer It is built from polygonal cells that have processes in the form of spikes and are still capable of reproduction.

3) Granular layer epidermis includes 3-4 rows of relatively flat cells containing grains of a special substance in their cytoplasm keratohyalin.

4) glitter layer built of flat cells in which the nuclei are destroyed, and the cytoplasm is saturated with a substance eleidin, which is formed from keratohealin.

5) stratum corneum the epidermis is the most superficial, it consists of dead keratinized cells, shaped like plates and containing a substance keratin.

In the epidermis, there is a constant renewal of epithelial cells. As you move up, the cells undergo keratinization (keratinization), completely necrosis and turn into horny flakes of the surface layer, which are sloughed off from the skin surface in the form of dandruff. There is a process of self-purification of the skin, which can be helped by methods of mechanical action.

2. Dermis(dermis). The main layer of the skin comes from the mesoderm, the middle germ layer. Here, fibers predominate and cells are present in a smaller amount. The main cell population is a young connective tissue cell - fibroblast. Fibroblasts produce products of the intercellular substance, and the intercellular substance is represented by fibers and an amorphous (shapeless) component. An amorphous substance is a gel or sol where metabolic products accumulate. Of particular interest in the intercellular substance is a protein-carbohydrate complex - proteoglycans, and in them - sulfated fractions of GAGs (glucosaminoglycans), which reliably cement the dermis fibers. With a deficiency of GAGs in the dermis, the strength and elastic-deformation properties sharply deteriorate, and it begins to crack.

Among fibrous structures, a special role in ensuring the biomechanical perfection of the skin belongs to collagen fibers, which make up 98% of all fibers. As you remember, the collagen fiber is based on the fibrillar protein collagen. Collagen is heterogeneous, there are 13 types. Type I collagen is the most abundant in the skin. The type of collagen can change with age, as well as in conditions of violation of the physical state of the body (for example, with inflammation, type III collagen is present). The ultrastructural unit of mature collagen is a subfibril, which combines into fibrils, which, in turn, into fibers, and those into bundles. The thickness of the beams, the peculiarity of their course, largely determines the strength and elasticity of the skin. Preferable for the skin are thin bundles of fibers with a tortuous course over thickened and straight ones.

Elastic fibers are located in the deep layers of the skin, they contain elastin protein. Elastic fibers accompany collagen fibers, but the bundles themselves do not form and are easily stained with fuchcin (brown, Hart's stain). They have pronounced elastic properties, which betray the proper elastic-deformation properties. There are very few reticulin fibers, the reticulin protein is not considered as an independent protein, it is referred to as type III collagen. It has a high modulus of elasticity. It is located between the epidermis and dermis, and also braids the hair roots and the glandular complex. The dermis also contains mature cells - fibrocytes and mast cells; there are hair roots and muscle cells (muscles - hair lifters - m.m. urrectores pilorum), sweat and sebaceous glands, there are a large number of blood and lymphatic vessels, as well as nerve fibers with their endings.

The dermis, or the skin itself, is the connective tissue part of the skin, divided into 2 layers: papillary and reticular. There is no clear boundary between them due to the constant transition of one layer to another. There are two equivalent approaches to isolating the layers of the dermis.

In one case, the separation of the layers of the dermis, in the study of mainly wild mammals, is carried out according to the depth of occurrence of the bulbs of the guard hairs and tubular glands. Thus, the papillary layer also includes derivatives of the skin.

In another case, usually when examining the skin of pets, the boundary between the layers of the dermis is established by an increase in the diameter of collagen bundles and fibrils, a change in the density of the tie, which increases as the papillary layer passes into the reticular layer.

1) Papillary, or pylar layer of the dermis located immediately below the basement membrane and consists of loose fibrous connective tissue. The protrusions of this layer - papillae protrude into the epidermis and give it the appearance of a wave.

2) Mesh layer of the dermis consists of dense irregular connective tissue. In areas of the body where the skin is under pressure, thick bundles of collagen fibers are usually well developed, the cells of the network are wide-looped. In areas of the body where the skin is stretched (the area of ​​the joints, the abdomen), the bundles are thin, the cells of this network are narrow-looped.

3. Subcutaneous layer, or hypodermis(tela subcutanea, subcutis). It is located under the reticular layer of the dermis, consists of loose connective tissue with an admixture of adipose tissue, containing a large number of blood and lymphatic vessels. Powerful shock-absorbing cushion, protection against shocks and shocks, maintains a constant body temperature of the animal. (In pathological conditions: edema - fluid accumulates; emphysema - gas, air accumulates).

Subcutaneous tissue consists of cells - adinocytes, located in loose connective tissue. Adinocytes are metabolically very active and their accumulation determines the thickness of the subcutaneous layer. The thickness of this layer varies greatly depending on the season, fatness, type of mammals and topography on the body. In well-fed animals, subcutaneous fat accumulates in this layer, which is consumed during starvation and lack of water. The lower border of the subcutaneous tissue runs along the superficial fascia of the body. On the eyelids, the scrotum, the fat layer is absent.

Phylo-ontogeny of the skin .

In phylogeny Vertebrate skin successively goes through a series of stages. At the lancelet(primitive organism) skin from just one layer built from columnar epithelium. In connection with landfall in amphibians the skin is already present 2 layers: outer two-layer epithelial, which develops from the ectoderm; and internal, connective tissue, which develops from the mesoderm. Further, in reptiles the outer epithelium becomes stratified, and

internal, connective tissue, develops and turns into the actual skin (dermis) with collagen and elastic fibers. In more highly organized animals, mammals and birds, further differentiation of the skin occurs. So, the outer, stratified epithelium turns into the epidermis and differentiates into 5 layers, and the base of the skin (dermis) into 2 layers.

In ontogeny The skin integument develops from 2 germ layers.

Its outer layer, the epidermis, is formed from the ectoderm, and the inner layer, the dermis and subcutaneous base, develops from the mesoderm. The skin is formed slowly. After the neural plate is isolated from the ectoderm, first a single-layer, and then a two-layer cover is formed, and then a multi-layer one, which differentiates into the main elements of the skin by the end of the embryonic period.

Species features of the skin.

The anatomical features of the skin are associated with the species of the animal. First of all, it concerns him thickness, which is closely related to environmental factors.

Animal species are arranged in the direction of decreasing thickness of their skin: buffalo, camel, cattle, pig, horse, donkey, small cattle. As for fur-bearing animals, the mustelid family (mink) has thicker skin than the canine family (fox, arctic fox). In dogs, the skin is thicker than that of the silver-black fox (140 microns) and especially than that of the arctic fox (97 microns). The thinnest skin of a rabbit and a squirrel. The latter animals are characterized by special adaptations in the dermis, the function of which has not been fully elucidated. The subcutaneous plate of a rabbit consists of 2 connective tissue layers, between which there is a layer of striated (striated) muscles, which worsens the presentation of the skin.

The sex of the animal affects the thickness of the skin: in males, the skin is always thicker than in females.

The thickness of an animal's skin depends on its topographic location. So, the skin on the lateral surface of the limbs is always thicker than that on its inner medial; and the skin of the back surpasses the skin of the abdomen in its load.

The structural components of the skin cover also have specific features: not only the epidermis, but also the dermis. So it is generally accepted to subdivide the dermis into 2 layers: papillary and reticular.

The papillary borders on the epidermis, according to Brown (1953), performs a trophic function, is organized according to the principle of fingers in a glove, which will be introduced into the latter. Particularly thick skin on its hairless surface. The thickness depends on the type of animal and varies significantly: 18-30% of the thickness of the entire dermis in cattle; 30-40% - horses; 50-60% - sheep; up to 70% in the red fox.

The dermis of the papilla is actively nourished. The epidermis has a significant impact on hair growth, changes in the structural organization causes hair loss, due to degeneration of the hair follicles. Therefore, by acting on the dermal papillae with medication, or with a magnetic field, hair growth can be corrected. In the papillary layer of the dermis, with a decrease in protein-carbohydrate complexes in it - proteoglycans, it is accompanied by a weakening of the bonds between individual collagen fibers, which do not have a strict order.

The second layer, the mesh layer, performs a mechanical function in the skin, consists of fibrous structures, the orientation of which is closely related not only to the type of animal, but also to the anatomical and topographical features of the distribution of the skin on its body. So in animals, depending on the anatomical and topographic features, there are 3 types of orientation, interweaving of the fibers of the reticular layer of the dermis:

1) Type of tie - diamond-shaped. Collagen fibers are represented by diamond-shaped figures, while the sides are oriented diagonally to the surface of the skin. On the back of the cattle. This kind of skin is characterized by extreme strength, but weak extensibility; justified by the functional holding load.

2) The type of tie is looped. Various configurations, has good extensibility, but little strength. Looped skin is located on the abdomen, which is necessarily associated with function. Predominant in small cattle and pigs.

3) Type - horizontally wavy. Parallel to the surface of the skin (tangentially). It occurs more often in fur-bearing animals (arctic fox, mink). Strength properties are not great, deformation-adaptive properties prevail.

Thus, the configuration of the fibers is different, which must be taken into account. Therefore, the disease has its own anatomical justification.

Similar information.

MINISTRY OF AGRICULTURE OF THE RUSSIAN FEDERATION

Federal State Budgetary Educational Institution of Higher Professional Education

“Kursk State Agricultural Academy named after Professor I.I. Ivanova"

Faculty of Veterinary Medicine

Department of Surgery and Anatomy

COURSE WORK

in the discipline "Animal Anatomy"

on the topic: "Skin of farm animals and birds"

Student Cherkasova Yu.O.

Teacher Everstova E.A.

Kursk - 2013

Introduction

The development of the skin

The general characteristic of an integument page - x. animals

1 The structure of the skin

2 Functions of the skin

3 Chemical composition of the skin

4 Physical properties of skin

Derivatives of the skin

3 Horn formations of the skin

Skin musculature

Features of the structure of the skin of page - x. animals

1 Features of the structure of the skin of the dog

2 Features of the structure of the skin of the pig

3 Features of the structure of the skin of ruminants

4 Features of the structure of the skin of the horse

General characteristics of the skin of birds

The structure of the skin of fur-bearing animals

1 Structure, hair coloring

3 Location of hair on the skin

Hygiene of care of skin and horns page - x. animals

1 Skin care

2 Horn care

Conclusion

List of sources used

Introduction

This course work is devoted to the study of the skin of farm animals and birds. Knowledge of the structure of the skin by a veterinarian is the basis for the treatment and prevention of diseases in animals and birds, since the skin is a vast area for stimulation or impact on a diseased organism.

The skin is a very important functional system. The skin and muscles form the body of the animal from the surface, give it shape and hold all the internal organs. The skin covers protect the body from external mechanical and chemical damage, exposure to temperature, desiccation, penetration of pathogenic microorganisms. The skin takes part in thermoregulation, gas exchange and excretion of decay products. Derivatives of the skin can participate in the formation of organs of movement (hooves), serve for grasping (claws), attack and defense (horns, needles, etc.), swimming (webs). The skin contains receptors of the organs of touch, it has many glands for various purposes (mucous, fatty, odorous, sweat, etc.). The skin of vertebrates, as a system of external organs, which has a direct connection with the environment, primarily responds to changes in environmental conditions. Therefore, the skin and its derivatives are extremely diverse in structure and function.

The development of the skin

In vertebrates, the skin develops from two germ layers; its outer layer - the epidermis (epithelial) is formed from the ectoderm, and the inner one - the base of the skin, the connective tissue and subcutaneous layer develop from the mesenchyme of the middle germ layer. In phylogenesis, invertebrates have an entirely ectodermal skin cover and it is represented by only a single layer of epithelium.

This structure of the skin is also preserved in the lancelet, but in the larvae of amphibians the epithelium is already two-layered. Starting with cyclostomes, the epithelium becomes multi-layered and a well-defined skin base with collagen and elastic fibers appears.

In vertebrates, a twofold differentiation of integuments is traced: primary - aquatic and terrestrial.

The first type is characterized by an abundance of unicellular glands in the epidermis and a tendency to form the basis of the skin (connecting layer) of the skin skeleton; for the second type, the appearance of horny derivatives of the epidermis in the form of scales, feathers, and hair is characteristic. Their glands are only multicellular.

Connective tissue gives an abundance of fibrous structures. For mammals, hair development and an abundance of skin glands become typical while maintaining the horny epidermal cover. In the subcutaneous layer, they have a large amount of adipose tissue.

Embryogenesis of the skin

The skin in the embryonic and prefetal periods is formed slowly. After isolation from the ectoderm of the neural plate, a two-layer epithelial cover is formed. During the prefetal period, the epidermis becomes multi-layered. By the end of the embryonic period, the skin becomes more complex due to the underlying mesenchyme, somatopleura, and somite dermatomes. The mesenchyme, located under the epithelial layer, forms the dermis. The formation of the skin and its derivatives basically ends in the fetuses of cattle by four months, in the fetuses of sheep by 2.5 - 3.5 months, and in the fetuses of pigs a little earlier.

The general characteristic of an integument page - x. animals

The skin (or general) cover - integumentum commune - is a dense, very strong outer shell of the animal's body with organs developed from it - derivatives of the skin: sweat, sebaceous, mammary and salivary glands, scales, membranes, hair, feathers, crumbs, claws , hooves, hooves and horns, as well as various folds, corneas and other formations.

Due to its external location, the ability to permeability, the development of blood vessels and nerves in it, the skin delimits the body from the external environment and thereby creates conditions for the formation of an internal environment. Due to constant contact with changing environmental factors (temperature, light, humidity, mechanical influences, electromagnetic, ultrasonic and other influences), the skin has a complex structure and has a high density.

1 The structure of the skin

Three layers of different structure and origin are distinguished in the skin: the epidermis is the outer layer, the base of the skin is the middle layer, and the subcutaneous layer is the deep layer (Fig. 1).

The epidermis - epidermis, or cuticle - is a thin layer consisting of squamous stratified epithelium, covered from the surface with a stratum corneum of dead cells. It is divided into two main layers: deep - producing and superficial - horny. Both layers in different places of the skin and in different types of domestic are built differently.

The producing layer - stratum basale - consists of living cells, which, once on the surface, become keratinized, turning into plates (scales) of the stratum corneum - stratum corneum. Horny plates are rejected in the form of so-called dandruff. Due to the rejection of scales, the skin is cleansed of pollution. The horny layer of the epidermis protects the skin from mechanical damage, drying out and is a good dielectric. Pigment cells lie in the deep layers of the skin of the epidermis. They give the skin a certain color, protecting it from excessive light exposure.

Five layers can be distinguished in the epidermis: basal, spiny, granular, shiny, and horny. The layers of the epidermis are built mainly from cells associated with the process of keratinization - keratocytes (epidermocytes).

In the area of ​​the natural openings of the animal's body, the epidermis passes into the integumentary epithelium of the mucous membranes. The epidermis is separated from the base of the skin by a thin, elastic membrane - the main membrane.

Rice. 1 Histological structure of the skin

A. 1 - epidermis, 2 - skin, 3 - dermis, 4 - hypodermis, 5 - hair shaft, 6 - funnel of the hair follicle, 7 - hair root, 8 - sweat duct, 9 - sebaceous gland, 10 - hair muscle, 11 - hair follicle, 12 - sweat gland, 13 - hair follicle, 14 - hair papilla, 15 - saphenous vein, 16 - subcutaneous adipose tissue.

B. 1 - proper stratum corneum, 2 - lustrous layer, 3 - granular layer, 4 - layer of spinous cells, 5 - cylindrical layer, 6 - connective tissue, 7 - excretory duct of the sweat gland.

The basis of the skin - derma, or the skin itself - corium, has the appearance of a highly developed layer of dense connective tissue, consisting of collagen and partially elastic fibers. The dermis is divided into papillary and reticular layers. The papillary layer bordering the epidermis - stratum papillare - increases the surface of the connection between the skin base and the epidermis and the area for accommodating the cells of its producing layer. Through the dense network of superficial nerve and vascular plexuses located in the papillary layer, metabolic and trophic processes in the epidermis and the perception of environmental factors are carried out. At the base of the skin are sweat and sebaceous glands, hair roots and smooth muscles - hair lifters. Smooth muscles are also contained in the nipples of the mammary glands, in the eyelids of the eyes and in the scrotum, and in the subcutaneous layer of the trunk, neck and head there are transversely striated muscles that strain certain areas of the skin and fascia. The base of the skin is connected to the underlying tissues through the subcutaneous layer.

The subcutaneous layer - tela subcutanea - consists of loose connective tissue, in which reserves of subcutaneous fat or fat can be deposited.

In general, the skin removed from the animal is called the skin, and freed from the subcutaneous layer during dressing is called fur (sheepskin); the cover, freed from the epidermis and subcutaneous layer, is called the skin.

Blood and lymphatic vessels of the skin have a complex structure and are arranged in four tiers. The deepest plexus between the subcutaneous layer and the fasciae of the body is represented by large vessels; the second - under the reticular layer at the level of the sweat and sebaceous glands, it is rich in venous anastomoses. At the border of the reticular and reticular layers, the third plexus branches, consisting of thin-walled vessels. And, finally, under the epidermis of the papillary layer of the dermis, the fourth tier is laid, which is rich in capillaries. The peculiarity of the blood supply and the structure of the vascular bed of the skin is associated with maintaining a constant body temperature of the animal. A special role in this belongs to arteriovenous anastomoses, which are most strongly developed in the skin of the auricles and on the limbs of cattle.

The lymphatic vessels of the skin originate from the subepidermal layer. They form superficial, medium and deep subcutaneous networks, from which lymph is collected through the lymphatic vessels to the regional lymph nodes.

The nerve elements in the skin of lower vertebrates already have various sensory cells and nerve endings. The skin receives a rich afferent and efferent innervation through the spinal nerves, which include fibers from the sympathetic nervous system for blood vessels and smooth muscle tissue. The composition of the nerves of the skin contains efferent nerve fibers for the glands and connective tissue - thin non-fleshy fibers with a diameter of 0.5-1.5 microns with a spindle-shaped nuclei of Schwann cells and fibers with a diameter of 2-3 microns with an oval or cigar-shaped nuclei of Schwann cells emerging from the sympathetic department and intended for innervation of smooth muscles. Afferent fibers are mainly represented by medium pulpy fibers with a diameter of 8-16 microns in large and 4-6 microns in small animals. In general, the number of non-fleshy fibers significantly prevails over the pulpy ones. Bundles of pulpy fibers form the main plexus in the hypodermis, which is connected to the plexus of the skin base.

2 Functions of the skin

Protective function

Mechanical protection of the body by the skin from external factors is provided by a dense stratum corneum of the epidermis, elasticity of the skin, its elasticity and cushioning properties of the subcutaneous tissue. Thanks to these qualities, the skin is able to resist mechanical influences - pressure, injury, stretching, etc.

The skin largely protects the body from radiation exposure. Infrared rays are almost entirely retained by the stratum corneum of the epidermis; ultraviolet rays are partially retained by the skin.

The skin protects the body from the penetration of chemicals into it.

Protection against microorganisms is provided by the bactericidal property of the skin. Healthy skin is impervious to microorganisms. With exfoliating horny scales of the epidermis, fat and sweat, microorganisms and various chemicals that enter the skin from the environment are removed from the surface of the skin. In addition, sebum and sweat create an acidic environment on the skin that is unfavorable for the reproduction of microorganisms. The bactericidal properties of the skin are reduced under the influence of adverse environmental factors - when the skin is contaminated, hypothermia; The protective properties of the skin are reduced in some diseases. If microbes penetrate the skin, then in response to this, a protective inflammatory reaction of the skin occurs.

The skin takes part in the processes of immunity.

respiratory function. Skin respiration increases with an increase in ambient temperature, during physical exertion, during digestion, an increase in atmospheric pressure, and during inflammatory processes in the skin. Skin respiration is closely related to the work of the sweat glands, rich in blood vessels and nerve endings.

suction function

The absorption of water and salts dissolved in it through the skin practically does not occur. A certain amount of water-soluble substances is absorbed through the sebaceous-hair sacs and through the excretory ducts of the sweat glands during the period of the absence of sweating. Fat-soluble substances are absorbed through the outer layer of the skin - the epidermis. Gaseous substances (oxygen, carbon dioxide, etc.) are easily absorbed. Separate substances that dissolve fats (chloroform, ether) and some substances that dissolve in them (iodine) are also easily absorbed through the skin. Most toxic gases do not penetrate the skin, except for blistering poisonous substances - mustard gas, lewisite, etc. Medicines are absorbed through the skin in different ways. Morphine is easily absorbed, and antibiotics are in small quantities. The suction capacity of the skin is enhanced after loosening and desquamation of the stratum corneum of the epidermis.

excretory function

The excretory function of the skin is carried out through the work of the sweat and sebaceous glands. In a number of diseases of the kidneys, liver, lungs, the excretion of substances that are usually removed by the kidneys increases. Sweating is carried out by the sweat glands and occurs under the control of the nervous system. The intensity of sweating depends on the ambient temperature, the general condition of the body. Sweating increases with increasing air temperature, with physical activity. During sleep and rest, sweating decreases. Sebum is secreted by the sebaceous glands of the skin.

thermoregulatory function

During the life of the body, thermal energy is produced. At the same time, the body maintains a constant body temperature, necessary for the normal functioning of internal organs, regardless of fluctuations in external temperature. The process of maintaining a constant body temperature is called thermoregulation. The layer of subcutaneous adipose tissue, fatty lubrication of the skin are a poor conductor of heat, therefore, they prevent excessive heat or cold from the outside, as well as excessive heat loss. The thermal insulating function of the skin decreases when it is moistened, which leads to a violation of thermoregulation. When the ambient temperature rises, the blood vessels of the skin integuments expand - the blood flow of the skin increases. At the same time, sweating increases with subsequent evaporation of sweat and the heat transfer of the skin to the environment increases. With a decrease in ambient temperature, a reflex narrowing of the blood vessels of the skin occurs; the activity of the sweat glands is inhibited, the heat transfer of the skin is markedly reduced. Thermoregulation of the skin is a complex physiological act. It involves the nervous system, hormones of the endocrine glands of the body. The temperature of the skin depends on the time of day, the quality of nutrition, the physical condition of the body and other factors.

3 Chemical composition of the skin

An important component of the skin is collagen. Of the total amount of lipids in the body, 2% of it is contained in the skin. Neutral fats and fatty acids of the skin make up 5%, and cholesterol - about 1/6. Water makes up 70-72% of the total chemical composition of the skin. The skin contains a significant amount of alkali metals: potassium, sodium, magnesium, calcium; metalloids - bromine, fluorine, iodine, phosphorus, arsenic (the latter is in the ionic state). The skin contains 1/3 of sodium chloride from its total volume in the body. The surface of the skin has an acidic reaction, pH = 3.2-5.2.

4 Physical properties of skin

Physical properties of the skin. The skin has high strength, great elasticity (elasticity). Skin and especially its horn derivatives are good dielectrics. The skin is characterized by great plasticity, variability, and it has a good regenerative ability.

Derivatives of the skin

Derivatives of the skin include: hair, crumbs, hard skin tip, skin glands. All these formations occurred mainly as a result of changes in the epidermis, hence they are also called epidermoidal formations.

1 Hair

Hair - pilus (Fig. 2) - is a keratinized, hard, but flexible and elastic thread originating from the cells of the epidermis. A huge number of such threads, protruding to the surface of the epidermis, gives the cover of mammals a hairy appearance characteristic of this class.

The filiform section of the hair that freely protrudes on the surface is called the hair shaft - scapus pili (Fig. 2-a). The rest of its basal part is immersed in a special deepening of the epidermis and is called the hair root - radix pili (d) - with a thickening at its base - the hair follicle - bulbus pili (f), - into which the connective tissue papilla, developed from the base of the skin, penetrates - papilla pili (l ). From the epithelial and connective tissues around the root, a rather complex case is formed - the root sheath and the hair bag.

In domestic animals, hair densely covers (with the exception of certain breeds of pigs) the entire skin, and only some areas are completely devoid of hair, such as hard skin fingertips, crumbs, horns, etc.

When considering the components of the hair root in the direction from the bulb to the beginning of the rod, gradual keratinization and loss of cell viability are striking, and the rod turns out to be completely keratinized. Here, therefore, the same process is observed as in the thickness of the epidermis of the skin. The difference lies only in the form of horn formations: in one case - in the form of a continuous horny cover of the cover, in the other - in the form of horn threads.

Just as part of the stratum corneum (sheath) of the epidermis falls off (flakes) from time to time, so the hair, upon reaching a certain size and maturity, grows old and, falling out, is replaced by new ones. The latter grow from the producing layer of the root sheath. This process is called molting, which is intensely manifested in the spring and autumn periods of the year. Long hair, for example, the manes and tails of horses, like the hair on a person's head, last for a relatively long time - from 3 to 5 years. Bristly hair in pigs and woolly hair in cultivated sheep are constantly replaced, at an indefinite time, as the hair follicle wears out. This is a permanent hair change.

Wild animals are characterized by a strict periodic change of hair, that is, annually in spring and autumn. Domestic animals do not have such a strict gradation of the seasons, but still an increased change occurs in spring and autumn. However, they also have a permanent change, so that the result is a mixed way of changing hair.

Hair can be of different thickness, structure and value. Ordinary covering hairs make up a hair garment, which, as a poor conductor of heat, serves as a reliable protection against bad weather. In most animals (horse, cattle, etc.) they are of moderate thickness and length, with a developed core. The latter in some mammals (in deer) is especially powerful, and therefore makes the hair more brittle.

Among the covering hairs there are thin, delicate, so-called wool hairs; in a number of animals they become predominant and even cover the entire body, with the exception of the muzzle and limbs (in domestic sheep)

Fig. 2 Hair structure

A. hair with a root sitting in the hair sheath; B. hair cut from the surface; a- hair shaft, b- epidermis of the skin, c-sebaceous gland, d- hair root, e- root sheath, f- hair follicle, g- hair core, h- cortical substance, k- hair cuticle, l- papilla, m- hair lifter, n- duct, o- tangle of sweat gland

At the same time, sheep's wool hairs come in various degrees of thickness, length, strength, elasticity and with an unequal relationship between the core and the cortical layer. They also play a protective role in the body.

There are relatively thick, coarse, so-called long hair, with a developed core and sinuses in the hair bag. Some of them perform a protective function, such as the mane and bangs of the horse, the beard of the goat, the hair of the tail and brushes of the horse; others, also sinusoidal, thick and relatively long hair, are unusually rich in nerve endings and very sensitive to the perception of tactile sensations.

The slightest vibration of the hair shaft as a long and elastic lever is transmitted to the root and nerve endings braiding the hair sheath.

This is the so-called tactile hair. However, this property is to a greater or lesser extent inherent in other hair. Hair shafts rarely stand perpendicular to the skin, and their roots in the thickness of the cover are located in an oblique direction. The laying of rods on the surface of the body with a certain direction is called the flow of hair - pulmina pilorum. In some limited areas of the body, the direction of the hair creates quite characteristic figures.

Hair can converge with loose tops to one point. Such a figure is called a convergent flow with an attraction point.

Hair can, on the contrary, diverge with tops in different directions from a certain point. Such a figure is usually called a divergent flow with a point of radiation. If the hair is slightly curved in one direction along the radiation circle, then a vortex figure or just a vortex is obtained - vortex pilorum.

The streams can converge for some distance on both sides of the tops of the hair, as a result of which a hair roller is created. This arrangement is called a convergent linear flow.

With a linear arrangement, the flows can diverge in opposite directions and create a hairline - a divergent linear flow. Sometimes there are more complex figures. The places of such groupings of hair are usually the head, especially the forehead, chest, iliac region, etc.

2 Crumbs

The crumbs - pulvini - in the form of simple cushion-like elastic thickenings of the skin on the volar (plantar) side of the paw are devices for resting on the ground. They also serve as an instrument of touch, as they are abundantly supplied with nerve endings. In mammals with increased grasping, and therefore tactile, function of the limbs (monkeys, etc.), the entire umbilical side, due to the abundance of nerves, is usually considered and even called the nervous side of the hand and foot. The general features of building crumbs are quite simple. The epidermis of the crumb is a thick hairless layer with a soft stratum corneum protruding on the surface in some mammals (for example, dogs) in the form of a large number of small (pinhead) elevations, in others - in the form of scallops, due to which the touch surface becomes rough, and therefore adapted to be held firmly in place. The epidermis has many excretory ducts of the sweat glands.

The basis of the skin of the crumb - corium pulvini - has relatively high papillae, in a number of which Meissner's nerve corpuscles are located, but, in general, it does not stand out for anything characteristic and therefore does not require a special description.

The subcutaneous layer of the crumb - stratum subcutaneum pulvini - is highly developed and somewhat peculiar: between the coarse bundles of adhesive fibers running in all directions with a rich elastic network, adipose tissue pads are laid. In total, an elastic and comfortable pillow is obtained, which serves as the main part of the crumb. It also contains the excretory sections of the sweat glands.

There are several such crumbs on the front paw (in predators): digital, or terminal, crumbs near the claw according to the number of fingers; metacarpal (metatarsal) crumbs at the distal end of the metacarpus (metatarsus) and carpal cushion in the wrist area.

3 Horn formations of the skin

In some areas of the skin of mammals, a number of derivatives of its epidermis develop, which have a horny structure. The horny formations include those areas of the skin in which the epidermis forms a powerful stratum corneum with a peculiar tubular or leaf structure. These include horns and digital organs in the form of claws, nails, hooves and hooves. The finger organs cover the dorsal surface of the distal end of the finger. In accordance with the plan of the structure of the skin, each finger organ - organuin digitale - consists of three layers: the epidermis, the base of the skin and the subcutaneous layer. A powerful layer of the epidermis forms a horny capsule of the tip, the shape and size of which depend on the structure, shape and function of the finger itself. The base of the skin is characterized by large papillae, which merge in the area of ​​the wall of the digital organ, forming papillae and ridges or highly developed leaves of the base of the skin, providing a strong connection of the horny sheath, as well as shock absorption from the ground to the limb. The presence of vascular plexuses at the base of the skin contributes to the powerful development of the epidermis. The subcutaneous layer of the tip (claw and nail) is located only in its proximal edge, i.e., in the area where the skin of the finger passes into the tip.

Claw - unguicula - a characteristic finger tip - an organ of digitigrade and plantigrade animals. The claw reaches its greatest development in predatory animals (especially in felines), in which it serves as an instrument of attack and defense, as well as for climbing trees. It has the shape of a hook with a pointed top (Fig. 3).

In phylogenesis, the claw appears already in amphibians. In reptiles and birds, it is well developed, and in various mammalian species, it is presented in the form of the above four forms.

The dog's claw consists of a claw roller with a claw groove, a corolla, a nail wall and a nail sole. The subcutaneous layer is developed only in the region of the claw fold. The claw roller - vallum unguiculae - represents an elevated area of ​​transition of the dorsal region of the skin of the finger into the claw. The epidermis and its base of the skin are immersed in the depth of the ungual groove of the third phalanx and form the ungual groove - sulcus unguiculae, in which the beginning of the horny capsule of the claw - radix unguiculae is located. The corolla and the claw wall - paries unguiculae - are located on the dorsal and lateral surfaces of the claw, and the claw sole - solea unguiculae - in the form of a narrow strip forms the distal wall of the claw.

The nail - unguis - represents a modification of the claw and is an accessory of primates.

The hoof - ungula - in the form of a strong, hard horny shoe, located at the distal end of the toe in one-hoofed animals, is a homologue of the claw. Together with the toe cushion, it provides cushioning and tireless running. Therefore, the horn capsule is placed almost vertically in the form of a cup with an extension on the supporting, plantar surface. This provides support not only on the sole, but also on the wall of the hoof. To the center of the sole, in the form of a wedge, grows a horny arrow of the digital crumb, which is tightly fused with the hoof. Due to the great elasticity of the crumb, when supported on the soil, it pushes the heel and side sections of the hoof wall of the horn shoe of the hoof and thus ensures the activation of the shock-absorbing mechanism - the hoof.

The hoof, like the skin, consists of three layers of the epidermis, the base of the skin and the subcutaneous layer. In the hoof there are four anatomically well-defined areas of the base of the skin and epidermis: the border, the rim, the wall and the sole, from which the hoof is formed.

The hoof border - limbus ungulae - in the form of a narrow strip, about 0.5 cm wide, is the transition from the hairy skin of the finger to the base of the skin and the horny shoe of the hoof. The hoofed corolla - corona ungulae - up to 1.5 cm wide is located distal to the border, covering the front and side stitches of the finger with it in a semicircle. They form the proximal - coronal edge of the hoof. The base of the corolla skin on the inner surface of the horny shoe leaves an impression in the form of a coronal groove - sulcus coronarius. The basis of the skin of the border and corolla consists of papillary and reticular layers. The papillae of the papillary layer of the skin base in these parts of the hoof are lowered down, as a result of which the stratum corneum of the border and corolla grows distally - down and forms a thick stratum corneum up to 1.5 cm thick, covering the horn of the hoof wall. The subcutaneous layer of the border and corolla in the form of dense connective tissue is well developed and is connected to the periosteum of the second phalanx of the finger - the coronary bone.

Hoof wall - paries ungulae - the most extensive part of the hoof. Forms the anterior and lateral surfaces of the hoof and, continuing beyond the heel angle, forms the bar wall. Proximally, it borders on the corolla, and distally, it takes part in the formation of the supporting area of ​​the plantar surface of the hoof. The epidermis and the base of the skin of the wall differ significantly from the rest of the hoof in the nature of the structure of the papillary layer, which has leaflets up to 4 mm long, running in parallel rows vertically from the corolla to the sole.

On the surface of each leaflet there are a number of smaller, secondary leaflets. The total surface of all leaflets is 1 m 2, due to which a strong connection of the leaflet layer of the skin base with its epidermis is achieved.

The epidermis of the wall - paries corneus ungulae - is represented by a leafy horn, which is light, light, i.e., a non-pigmented horn. From the surface, the horny leaflets merge with the tubular horn of the corolla. Thus, the wall horn is the inner layer of the horn shoe. The distal edge of this horn on the sole of the hoof is projected as a white line - linea alba ungulae, or a leaf zone - zona lamellaturn, - the place where forging nails are driven in.

The hoof sole - solea ungulae, like the hoof wall, does not have a subcutaneous layer, and the base of the skin of these sections, with its periosteal layer, fuses directly with the periosteum of the hoof and coronoid bones of the finger. The papillary layer of the base of the skin produces a powerful tubular horn of the sole - solea cornea ungulae, which is not inferior in the degree of development and strength to the tubular horn of the corolla. In general, the epidermis of all four sections of the hoof forms a horny capsule, or the horny shoe of the hoof, the wall of which is formed by the stratification of three horny layers: the outer layer of the tubular horn of the border, covering the horn shoe with a thin and shiny layer - glaze, the middle layer - the tubular horn of the corolla, the most strongly developed, and the inner layer - the leafy horn of the wall. The tubular horn of the sole serves as the bottom of such a cup.

On the horn capsule of the hoof, two edges are distinguished - coronal proximal and distal - free, or plantar. The dorsal surface of the shoe is divided into a toe section, which passes into paired lateral sections, into the heel sections and into the heel angles.

Rice. 3 Schematic of the solid dermal tip

Crocodile claw; 2, 2 "- claw and finger crumb of carnivores; 3, 3" - claw and finger crumb of a monkey; 4, 4 "-nail and digital crumb of a person; 5, 5" - hoof and digital crumb of a horse; a-claw, nail and hoof walls; b-claw and nail roller and hoof rim with hoof border; c, c "- claw, nail and hoof soles; d-3rd phalanx of the finger; e, e" - digital crumb; f-claw groove; g-2nd phalanx of the finger.

The heel angles then pass into the bar, visible from the side of the sole. The hoof sole, on which the animal rests, is divided into the body and paired branches, between which the digital crumb is wedged - an arrow.

The blood supply and innervation of the hoof are carried out from the volar and, respectively, from the plantar (on the pelvic limbs) vessels and nerves, which have powerful neurovascular plexuses and corresponding nerve endings at the base of the skin of the rim, corolla, wall and sole.

The hoof of cattle and pigs corresponds to the hoof of a horse, but divided in half. They have no collars, and their soles are poorly developed.

Horns - cornu - hollow horn formations that have developed on the horny processes of the frontal bones. These processes develop after the birth of animals and consist of two layers: the base of the skin and the epidermis. Later, these rudiments of the horn fuse with the basis of the skin with the periosteum of the processes of the frontal bones. The germ layer of the epidermis produces a very strong tubular horn. In whole-horned animals, the horn is a continuous bone formation. On the horn, the root of the horn is distinguished - basis cornus, the body of the horn - corpus cornus and the top of the horn - apex cornus.

The development of the stratum corneum of the horn is influenced by the living conditions of the animal, the state of health, fatness, pregnancy, etc. An increase in the function of the germ layer leads to the formation of special influxes - rings on the horns, and a decrease in function, on the contrary, leads to the formation of interceptions. In cows, the rings and interceptions on the horns are judged on their age or number of pregnancies. The shape of the horns of cattle is round, with varying degrees of curvature; in a ram, the horn is somewhat flattened and curved spirally; in goats, it is flattened laterally, the front edge is pointed, the top is bent back.

4 Skin glands

Derivatives of the epidermis, deepened into the thickness of the cover, form a variety of skin glands. It is clear that in vertebrates, the cover of which is always surrounded by a liquid medium, as, for example, in fish, there are no multicellular skin glands at all. Even in mammals that have adapted to life in the sea - sirenians (manatee, dugong, etc.), cetaceans (sperm whales, dolphins, whales, etc.) - the cover also does not contain glands.

In amphibians, on the contrary, the general cover is almost everywhere abundantly supplied with glands of a twofold type: some of them, relatively small mucous membranes, secrete an almost homogeneous mucous and even sticky secretion; others, more voluminous, whose cells during secretion increase so much that they fill the lumen of the gland, secrete a granular, cloudy, sometimes odorous, sometimes caustic, and sometimes even highly poisonous secret. It is characteristic that in both types of glands, the main membrane has a layer of contractile cells.

Mammals have two types of glands.

Another type of gland has an alveolar (saccular) structure. Glandular cells in several layers fill the alveoli and gradually disintegrate when secretion is produced. Their secret is thicker, with a significant amount of fat. These glands do not have a layer of contractile cells (sebaceous glands). Skin glands are named for the nature of the secret they secrete: sebaceous, sweat and mammary glands.

The sebaceous glands-glandulae ceruminosae-are scattered throughout the cover and in the vast majority are associated with the hair sheath, into which they open with excretory ducts. Their secret - sebum - cerumen - lubricates the growing hair and the surface of the integument when released, as a result of which the hair loses some of its hygroscopicity and becomes, like the stratum corneum of the epidermis, softer.

Sweat glands - glandulae sudoriferae - are also scattered throughout the body and are also mostly connected by excretory ducts with hair sheaths, but can also open directly to the surface of the cover. The strength of their distribution and development among mammals varies considerably. Even in domestic animals, such as, for example, in horses and sheep, they are much more common, while in dogs and especially cats, they are less common. The secret of the glands is sweat-sudor.

The mammary glands - glandulae lactiferae - are one of the signs of the organization of a whole class of vertebrates. Due to the presence of mammary glands, this class was called mammals. The appearance of the mammary glands is associated with the birth of live cubs, unable to feed on their own in the initial period of life.

The mammary glands at first developed, in a limited place of the general cover - on the paired folds of the abdominal wall behind the navel. These folds - right and left - coalesced with free edges along the midline of the abdomen and formed a skin bag in which the helpless cub hid for the first time after birth. Glands developed from the milk field, and their secret, apparently, flowed down from the excretory ducts along the tufts of hair and was licked by the cubs. Subsequently, due to multiple pregnancies, the glands multiplied in number and appeared in pairs on the abdominal and even thoracic surface of the integument, to the right and left of the midsagittal line. The cubs sucked out the secretion of the glands. Suction was facilitated by the formation of nipples, beyond which the glandular tubules grew strongly, creating a mound, or body of the gland.

In other animals, on the contrary, glands remained active at the caudal end of the abdomen, between the thighs. On the udder - (in ruminants, horses, etc.) uber - usually several mounds of one side merge with the corresponding pairs of the other side into one large complex body with the teats preserved (in ruminants, Fig. 4-G). However, in some mammals, when two mounds of one side merge along the milk line, the nipples also merge (in horses, Fig. 4-F).

Fig.4 Scheme of the mammary glands

A - a diagram of the beginning of the development of the mammary glands in the form of milk lines on a transverse section of the abdomen; C - development of milk offspring (c) from the region of the milk pocket (b); C - the formation of a true nipple; E - cross section of a pair of multiple glands in dogs and pigs; F - cross-section of connected hills in horses; G - complex body of the gland of cattle; c, c’, c” - milk tubules; b - glandular tissue; d - glandular field, e - glandular field that formed the nipple (C) or channel and cistern.

Finally, in the third species of animals, a more primitive state is observed, i.e., mounds with nipples are preserved in pairs in significant numbers over the entire ventral surface of the chest and abdomen, as, for example, in pigs, carnivores, etc. A series of such milk mounds with their own nipple is called multiple change.

On the gland as a whole, a body-corpus-and a drooping process-nipple-papilla are distinguished, and the body can be complex, i.e., consist of several connected milk hills. As in any organ, the mammary glands have a skeleton, or stroma, and the main functioning part is the parenchyma.

The skeleton, or stroma, of the gland is built from connective tissue. Covered with fascia and skin, it directly dresses the body of the gland in the form of a shell, and a large number of elastic fibers run through the collagen bundles. Significant partitions extend from this shell deep into the body, dividing it into lobules. From these partitions inside the lobules, in turn, delicate connective tissue bundles branch off, which already envelop directly the glandular tubules and alveoli that make up the parenchyma of the gland. The partitions of the skeleton also serve as a place where nerves and vessels are located, bringing nutrients and carrying away metabolic products.

In the function of the gland, two points are noted: 1) the secretion of milk by the cells of the working tubules and alveoli; 2) allocation of the developed secret (milk) through the system of excretory tracts. Isolation is due to the presence of special contractile elements almost along the entire path of the gland. They are located under the cells lining the lumen both in the alveoli and in the excretory ducts, and in addition, the latter are accompanied on the outside by smooth muscle tissue throughout their entire length. It is concentrated in a particularly large amount in the wall of the nipple, at the end of which it forms a sphincter, i.e., an exit obstructor. The function of the mammary gland is determined by many factors, in particular the ratio between its stroma and parenchyma. It goes without saying that the milk udder must have a well-developed parenchyma, but overdevelopment in this direction inevitably entails the insufficiency of the skeleton, and the latter plays, although a secondary, but far from unimportant role. Its weakness, first of all, leads to a poor supply of blood vessels to the udder, as well as to a relatively low resistance to pathogens.

The reverse relationship, i.e., a strongly developed skeleton with a poor parenchyma, characterizes a well-protected, resistant, but little milk udder. From this it is clear that the combination of stroma and parenchyma in both directions should be recognized as the best relationship.

Even in the udder parenchyma itself, the size of the lumen of the alveoli and tubules is not the same in different races. Wide alveoli in the total mass cause a decrease in the territory of functioning cells.

Skin musculature

The skin has both striated and smooth muscles.

The striated muscles located in the subcutaneous layer are very extensive and are localized on the trunk, neck and head. With its help, local skin folds are formed, fasciae are tightened, foreign particles, insects, etc. are shaken off the skin.

Smooth muscles are found in the form of lamellar shells, as well as small muscles.

In the form of whole plates, smooth muscles are located: in the scrotum - the muscular-elastic membrane - tunica dartos, - in the nipples of the udder, in the eyelid - m. tarsalis. Individual miniature muscles are scattered all over the skin near the hair follicles. These are the so-called hair lifters-mm. arrectores pilorum. They lie so that they form an obtuse angle with the surface of the skin, start from the deep parts of the hair bags, rise to the epidermis and end in small elastic tendons. On their way, their muscular abdomen surrounds the sebaceous glands and the excretory duct of the sweat glands. Due to this position, the muscles can straighten obliquely lying hair roots during contraction, and, consequently, their rods also rise on the surface. At the same time, the muscles help to remove secretions by pressing the sebaceous glands and block the excretory ducts of the sweat glands. This action can be seen from our own experience: with a strong cooling of the body, point elevations (muscle contractions), the so-called "goose ripples", appear on the skin. At the same time, the sweat glands are closed, and their secret does not enter the surface of the skin, therefore, the evaporation of the secret and excessive cooling of the body surface stop. In addition, in hairy animals, hair rises.

Features of the structure of the skin of page - x. animals

1 Features of the structure of the skin of the dog

Skin covering. The basis of the skin in some breeds of dogs is moderately thick and relatively rough, in others it is thin, soft and elastic. The coat is generally thick, but extremely variable in length, hardness, smoothness or curlyness.

The hair is most densely located on the back, as well as on the dorso-lateral surface of the limbs, where the base of the skin itself is thicker than on the abdomen and medial surface of the limbs.

On the lips, as well as above the eyes, often in the intermaxillary region and on ganaches, long sinus hairs are developed with increased sensitivity in the roots.

In some breeds, the tail hairs reach a considerable length (fluffy tail). Hair is absent on the nasal planum. Special figures of hair streams are observed on the neck, front and lower surfaces of the chest, on the upper links of the limbs.

Hair in dogs are connected in groups of 4-8 pieces in such a way that their bulbs in the depth of the cover stand one by one near the other, and towards the surface, i.e. towards the epidermis, they come closer and appear outward from one common hair funnel. In this case, very often one of the hairs of the group turns out to be the most strongly developed: this is the main hair of the group, and the rest, weaker, are side hairs.

Crumbs and claw.

Dogs have: carpal, metacarpal, metatarsal and digital crumbs.

Carpal crumb - pulvinus carpalis (Fig. 5-a) - lies in the form of a small skin elevation on the volar surface of the wrist near the accessory bone. Represents a rudiment that allows us to assert that the animal in its past was plantigrade, when this crumb also served as a support on the ground.

The metacarpal crumb-pulvinus metacarpalis (b) is the most significant in size, approximately heart-shaped. It is located in the region of the distal end of the metacarpal bones and the beginning of the first phalanges of the fingers. Its base is turned towards the wrist, and the top is slightly extended between the fourth and second finger crumbs. When attacked, it is mainly the joints of the first phalanges that rest against it. The same crumb is present on the pelvic limbs - metatarsal crumb - pulvinus metatarsalis. The metacarpal crumb is connected with the first phalanges of the 3rd and 4th fingers with a special suspension ligament.

Finger crumbs - pulvini digitales (c) - are present on each finger in the region of the 2nd and beginning of the 3rd phalanx. It is strongly advanced towards the claw from the plantar side.

Fig. 5 Finger crumbs of a dog

On the claw - unguiculus - they distinguish: a claw roller with a nail groove, a claw wall with a corolla and a claw sole.

The claw roller is the transition area of ​​the skin of the finger to the claw. Here, in addition to the epidermis and the base of the skin, there is also a subcutaneous layer (hence the base of the skin is folded into a bone claw groove). The claw roller covers the base of the claw and passes into this latter towards the digital crumb. The epidermis from the region of transition to the gutter gives a thin stratum corneum to the horny wall of the claw and dresses the latter from the surface in the form of glaze. From the roller, the epidermis and the base of the skin are bent into the bone groove of the 3rd phalanx and form the ungual groove. It is especially deep in cats. From the depths of the gutter, the base of the skin with its epidermis appears on the ungual wall and turns here on the dorsal surface into the base of the skin of the corolla (x), being part of the claw wall. lateral surfaces of the claw, and the corolla appears from the depths of the nail groove.

The claw sole (e) is narrow and localized on the plantar side of the claw.

The skin layers are distributed as usual: subcutaneous layer, skin base and epidermis.

The subcutaneous layer exists only at the site of the transition of the skin to the claw and does not represent anything special in its structure.

The base of the skin of the claw is firmly fused everywhere with the periosteum of the 3rd phalanx. On separate parts of the claw, it is built as follows:

The base of the corolla skin - corium coronae (k) - originates as a wide strip in the depths of the nail groove, then, gradually narrowing, thickens on the convex dorsal surface of the 3rd phalanx and stands out here in the form of a significant hook-shaped appendage, firmly connected to the periosteum of the phalanx. All this thickening serves as the basis for the corolla skin.

Papillae based on the skin of the corolla are developed only in the depth of the trough, the rest of its surface is smooth. The basis of the skin of the wall - corium parietale (l) - is already divided by the basis of the corolla skin passing along the back into the right and left sections. The portions of the base of the skin of the wall are insignificant in terms of the occupied area, they are located on the sides from the roller-like corolla to the plantar surface. Parallel leaflets of the papillary layer stretch in gentle arcs along the lateral surfaces of the 3rd phalanx.

The base of the skin of the sole - corium soleare - is quite massive and bears papillae, directed downwards with their tops.

The producing layer of the epidermis of the claw is located on the papillae and lamellae of the base of the skin of the claw. It produces the stratum corneum, which serves as the horny capsule, or horny shoe, of the claw. On the claw, the horny capsule breaks up into: the horny wall and the horny sole of the claw.

The horny wall of the claw (paries cornea unguiculi) is a complex formation. It covers the claw from the dorsal and lateral sides and is a merger into one whole of the stratum corneum of the wall itself - stratum parietale - with the coronal stratum corneum - stratum coronarium.

The coronal stratum corneum is the densest and most durable corneal part of the capsule. It begins with a wide root in the depths of the groove, towards the back of the claw, gradually narrowing, thickening and ending in a curved point, hanging at the top beyond the claw sole.

The stratum corneum of the wall (e) is less dense. It merges without borders with the coronal layer, and with free edges adjoins the horny sole from the sides and even hangs down somewhat on the sides, partially covering the sole.

The horny sole of the claw -solea cornea unguiculi (e) - is relatively narrow, consists of a tubular loose horn and develops from the producing layer lying on the papillae of the base of the skin of the sole.

Thus, a significant difference between the claw of dogs and the claw of a more primitive structure (in reptiles) is the presence of a nail rim as an additive, which grows entirely towards the claw wall and gives it greater strength. This should be especially noted, since we have seen that in ungulates this process deepens even further, giving rise to a coronal stratum corneum over the entire width of the wall. In dogs, the claw can touch the soil with its tip and therefore becomes dull with age.

2 Features of the structure of the skin of the pig

The skin, with the exception of the subcutaneous layer, is in general relatively thin, from 1.5 to 3 mm (in purebred white pigs, from 0.6 to 1.6 mm). In the region of the ventral side of the neck, it is thickest. The epidermis on the back is thinner than on the lateral sides of the limbs.

Rice. 6 Pig fingers on the volar side

hanging hooves (2nd and 5th) fingers; b- finger crumbs; c-hoof wall; e-interhoof gap.

The subcutaneous layer has a large number of fat cells. In cultivated fattened pigs, it reaches a huge thickness, measured in centimeters; this is the so-called speck. In males, by the period of puberty, from the end of the neck along the sides of the shoulder and shoulder girdle (but not rising to the withers) and further on the side wall of the thoracic region, the so-called shield develops towards the abdominal wall. It consists of dense connective tissue bundles with significant pads of fat lobules. The shield is localized in the reticular layer of the base of the skin and extends deeper, capturing the subcutaneous layer. With age, it increases posteriorly. This seal is probably associated with sexual activity and protects males during a fight.

In domestic pigs, hair is more sparse than in other animals, and in some breeds the skin is almost bare. Between the comparatively long and hard guard hairs there are thin and soft hairs. Coarse long hair is especially strongly developed on the dorsal contour of the withers and back and resembles a mane. This is the so-called bristle. The tops of these hairs are split into thin threads; the number of the latter is not the same in different breeds. There are breeds of pigs that are very hairy and even curly, with relatively soft hair.

From the proboscis on the nose along the dorsal contour posteriorly to the top of the tail there is a linear divergent stream of hair. The flow of the same nature is directed from the lower lip to the region of the larynx. Smaller streams are also observed in other places of the head, on the knee crease, etc.

The hooves are similar to those of cattle. They look like halves of a truncated cone with convex marginal and straight interdigital sides. Along the upper border there is a hoof rim with a hoof border, the horny layers (glaze and coronal horn) participating in the formation of the hoof wall.

The digital cushion is considerably developed and protrudes far behind into the area of ​​the plantar side with elastic subcutaneous and soft horny layers, so that the hoof sole occupies a relatively small strip of the anterior part of the plantar side of the hoof. Sometimes both leaning hooves merge into one formation.

skin glands

The sebaceous glands are more sebaceously developed in wild pigs. On the skin between the hooves and at the entrance to the preputial sac, they are very large, from 0.5 to 1 mm. The sweat glands in the secreting area do not curl as tightly in a ball as in horses. A significant accumulation of sweat glands is located between the hooves. At the proximal end of the carpal joint on the medial (closer to the volar) side, there are so-called carpal glands - glandulae carpales - in the form of small depressions; at the bottom of them, numerous glomerular glands open. In a fairly noticeable number of glands also accumulate on the chin - the chin glands. The mammary glands of pigs represent a type of multiple udder and are distributed in pairs in the chest and abdomen up to and including the groin. On each side there are 5-8 milk hills (usually 6), each with a short nipple. The nipple usually has two (rarely three) teat canals and small cisterns.

Males also have a small number of rudimentary nipples.

3 Features of the structure of the skin of ruminants

dermal farm animal hygiene

In cattle, the skin is generally thicker than in other domestic animals, the connective tissue bundles are more massive and the elastic fibers are larger. The guard hairs are short (slightly longer than in horses). In the forehead area, they are often curly. The tail only at its end carries a significant tuft of long hair - a brush. The skin forms a characteristic fold-breast.

In sheep, the skin is thin and delicate, on the back and back of the head it is thicker. Their guard hairs vary considerably, depending on the breed and even on the area of ​​​​the body.

It is customary to single out:

) short coarse hair containing a core; they are located as covering hairs on the facial area (muzzle) of the head and on the limbs of domestic (non-merino) sheep; in wild races they also cover the torso;

) wool, consisting of thin, more or less crimped hairs without a core (or only with small islands of it). The wool covers (together with the awn) the body of domestic sheep, forming a fleece. They protrude from the epidermis in rounded groups of 10-12 hairs. In Merino sheep, the fleece consists of only fine hairs, that is, more or less uniform, and covers almost the entire body;

) awn - long, coarse, uncurled hair with a core (exceptions are rare); their bulb sits deep in the skin. These hairs of domestic sheep are mixed with wool, that is, they are part of the fleece. Merinos do not have them. In some breeds bred by selection of factory individuals, the qualities of wool and awn are so close that in appearance the entire wool seems almost uniform, as, for example, in Tsigai and Tushino meat sheep.

Hooves and crumbs

Cattle and small ruminants rest on the soil with the last phalanges of the 3rd and 4th fingers. Their hard skin tip is called a hoof. They also have abortive hooves that do not reach the ground. The shape of the hoof is, as it were, half of the horse's hoof and closely resembles the latter in its structure. The hoof border, hoof rim and hoof wall are developed in the same way as the corresponding parts of the horse's hoof, and only the hoof wall differs in that it has no bar parts.

The general features of the structure of the digital crumb are the same as those of a horse. In cattle, it, tapering, continues along the sole, but does not form an arrow (like in a horse). In small ruminants, the digital cushions protrude more significantly into the plantar surface, leaving a small forward area for the claw sole. The nature of the setting of the fingers in cattle varies widely. Horns. The frontal bones of ruminants have bone processes, which serve as a support for the cornua horns. The bone processes themselves are of skin origin, and their rudiment in embryonic life is soldered with the frontal bones into one whole.

The skin that covers these processes has only two layers - the basis of the skin and the epidermis.

The basis of the skin of the horns - corium comus - adjoins directly to the periosteum of the periosteum of the frontal processes. Its papillary layer is equipped with rather strongly developed papillae. From the base towards the end of the horn, the papillae become gradually higher, less frequent, and stand obliquely towards the top of the horn. At the top are the highest and most frequent papillae.

The producing layer of the epidermis, which covers the papillary layer, produces a very strong tubular stratum corneum, which is formed into a horny sheath, or horn in the close sense of the word.

On the horn, a root, body and top are distinguished. The root of the horn - radix connus - lies on the border with the skin of the forehead. The stratum corneum here is comparatively thin, soft, and pierced even with sparse hair. The body of the horn-corpus cornus-is a continuation of the root to the top of the horn-apex cornus. The stratum corneum gradually thickens and on the outer surface form circular ridge-like elevations - horny rings, between which slight interceptions are observed. They indicate a periodic increase in the work of the producing layer, associated with the influx of a new ring. In cattle, the rings are outlined in relief only at the root of the horn and disappear towards the top; in cows, their appearance is associated with the period of pregnancy. After each calving, a new ring appears at the root. In sheep, the rings are clearly visible all over the horn.

The shape of the horn is determined primarily by the outline of the bone process, and then by the uneven growth of the horny mass. If there is an increased production of the horn on one side, then the tip will deviate in the opposite direction. Such local growth enhancements allow the antlers to spiral, which is not uncommon. In cattle, the horns are more or less rounded and varied in shape, in sheep they are somewhat flattened, and in the majority one side is flat and even concave in length, and the opposite, on the contrary, is convex. This bulge is noticeably pronounced and gives the cross section of the horn an irregular trihedral shape. The horns themselves wind from the root to the top in a steep spiral to the sides of the head. In goats, the horns are slightly flattened from the sides, and the anterior convex edge is sharper than the posterior one. They have the shape of a gentle arc, directed backward by the apex.

Skin glands. In terms of richness of sebaceous and sweat glands, the skin of ruminants is not inferior to that of horses, but the sweat glands are not so massively developed (they wriggle less). Cattle sweat visibly on the facial region of the head-muzzle.

The nasolabial glands (glandulae nasolabials) of cattle and the glands of the nasal planum of small ruminants (glandulae planonasales) are characterized by highly curled (glomerular) excretory tubes. Their excretory ducts, after the excretory section, have so-called insertion sections, and they are followed by newly secreting sections and, finally, the actual excretory ducts. Thus, these glands with their excretory ducts resemble the structure of the salivary glands (see digestive organs). In sheep, sweat mixes with sebum and forms “fatty” or “oily sweat waves” in thick wool.

Features in sheep

The lacrimal fossa, fossa infraorbital, is approximately 1 cm deep and lies in front of the medial canthus of the eyes. It shows traces of thin hairs, in the vagina of which large sebaceous glands open. The latter form a layer about 1-2 mm thick, and under them lie the glomerular glands. The general viscous secret, due to drying, takes the form of a yellow greasy smearing mass. The inguinal pocket - sinus uberalis (mammaricus) - lies in females on the sides of the udder, and in males in the inguinal region in the form of a slit-like depression. The base of the skin and the flaky layer here are significant in thickness and are covered with a yellow fatty crust. Fine hairs in the deepening of the pocket are provided with relatively highly developed sebaceous glands. The glomerular glands are also very massive.

Interhoof sacs - sinus interdigitalis - represent a depression between the fingers, the opening of which, 2-4 mm wide, opens at the level of the second joint of the fingers closer to the front. In the wall of the sac there are delicate hairs and numerous sebaceous and glomerular glands, the secret of which fills the cavity.

Mammary gland

The udder of uber-ruminants (Fig. 7.8) is located between the thighs in the pubic region. In cattle, compared with other domestic mammals, the complex body of the gland and the nipples are most strongly developed. The udder of cows resulted from the merger into one massive whole of three paired glandular hillocks with three pairs of nipples, of which the posterior pair remains underdeveloped - abortive, and more often completely disappears, so that only two pairs remain active. However, sometimes the average pair turns out to be abortive.

Rice. 7 Half diagram of a cow's udder

A- skin, B- lobules of the gland, C- milk passages, D- nipple canal, D- cistern

The border of the right and left halves is a flat median sagittal sulcus - sulcus sagittalis. Without taking into account a pair of abortive nipples, it is only possible to conditionally divide the right and left halves across into cranial, or abdominal, and caudal, or femoral. Each of them has its own nipple with an excretory duct. The glandular mass of either independent quarter, both outside and in the thickness, does not reveal clear boundaries, except for a weak transverse furrow on the surface between the nipples. The complex body of the udder comes in various shapes (Figures 8 and 9).

Fig. 8 Cattle udder

A - evenly developed "femoral udder", B - it is also behind, C - uniform abdominal udder, D - primitive udder

The udder is covered with a relatively delicate skin, passing to it from the side of the abdomen and the medial surfaces of the right and left thighs, with thin and generally scarce, and only in uncultivated breeds, abundant hair (Fig. 7-D).

On the caudal surface of the udder towards the genital slit, clear sheer folds of skin often protrude with noticeable linear streams of hair, due to which the so-called milky mirror is outlined.

In addition to the skin and directly below it, the udder is dressed in a superficial membrane that serves as its fascia. The superficial fascia of the udder is a continuation of the udder of the superficial fascia of the abdomen - fascia superficialis abdominalis.

The yellow abdominal fascia gives off a significant layer with a large number of elastic fibers in the area of ​​the white line of the abdomen towards the base of the udder. It penetrates between both halves of the body of the udder, forming the udder septum - septum uberis - and at the same time serves as a supporting ligament of the udder - ligamentum suspensorium uberis. In addition, there is its own connective tissue capsule with adipose tissue, from which connective tissue plates and cords extend into the thickness of the udder, creating its skeleton.

On the section of the udder, small (0.5-5.0 mm) rounded or irregularly angular areas are visible, separated by layers of the connective tissue skeleton. These territories represent the glandular lobules of the udder - lobuli uberis. From the layers that delimit the lobules, the skeleton also penetrates into the lobules in the form of tender bundles; they braid lying-here working tubules or alveoli. The strength of the development of the connective tissue skeleton and glandular tubules in the lobules is not the same.

Numerous working tubules and alveoli open into the excretory ducts; the latter, connecting with each other along the way to the nipple, form milk channels, already visible to the naked eye. Towards the base of the nipple, they form the main milk passages - ductus lactiferi - which greatly expand near the base of the nipple and open with oval or slit-like holes into its cavity, called the milk tank - sinus lactiferus s. receptaculum lactis.

Nipples - papillae uberis (Fig. 8) - are rather long (6-9 cm), approximately cylindrical in shape, with a slightly expanded base and a rounded top; on it, a short (about 1 cm) nipple canal, ductus papillaris, opens with one hole. The basis of the skin of the nipple is rich in elastic fibers and fits snugly to the tissue surrounding the epithelium of the nipple cavity, i.e., the cisternae. The latter is an expansion of the milk passages and is more often localized within the nipple, but sometimes it extends for some length beyond the base of the nipple into the body of the gland. The inner surface of the tank, if it is not overflowing with milk, is collected in small folds and niches.

Fig. 9 Different shapes of udder teats in cattle

A - cylindrical (meat) nipple, B - conical nipple, C - expanded at the base of the nipple. The connective tissue wall of the nipple contains bundles of smooth muscle fibers. They are directed in their main mass not longitudinally, but intertwined with each other. Deeper, i.e., closer to the lumen of the nipple, the bundles penetrate, going approximately circularly. In addition, the wall is rich in blood vessels, and the veins even form a semblance of a cavernous body, i.e., in places, expanding, intertwine into a dense network. At the top of the nipple within the location of the nipple canal, deep bundles of muscle fibers, surrounding the canal with a ring, form its sphincter. The nipple canal is lined with stratified squamous epithelium with distinct papillae of the skin base. The skin of the nipple is hairless and does not contain any sebaceous or sweat glands in cows.

In goats, the udder consists of two (right and left) halves with one teat each. Accessory (caudal) nipples are mostly absent. The udder is strongly retracted. The long, well-developed nipples deviate slightly forward and to the sides and also have a cistern and a nipple canal.

Sheep have a two-part udder; additional abortive nipples (caudal) are not common. The nipples are more distant from each other and the tops are noticeably turned to the sides. There is a cistern, but less extensive than that of a goat.

4 Features of the structure of the skin of the horse

The thickness of the skin of horses varies depending on the breed, sex (thinner in mares), age (thicker in adults) and place on the body. In general, it is thinner than that of cattle, but thicker than that of other domestic animals. The skin is especially thick in the area of ​​the mane, i.e., in the upper contour of the neck, as well as on the ventral surface of the tail. It is somewhat thicker on the head and back than on the abdomen; on the anterior and lateral surfaces of the limbs it is thicker than on the posterior and medial. In thin-skinned horses, the parts lying under it are more clearly outlined, such as, for example, bony protrusions on the limbs, muscles and tendons, vessels on the front of the head, on the abdomen, on the limbs. In general, the skin is firmly attached to the body, but in some places there are noticeable folds, such as the knee crease.

Covering hairs are relatively short and straight (rarely slightly curled), tactile (sinuose) are common on the head: on the upper and lower eyelids, on the cheeks, lips, chin, and in the submandibular space.

Long hair forms: bangs-cirrus capitis, mane-iuba, tail hairs-cirrus caudae (not on the ventral surface of the tail), brushes-cirrus pedis-on the back surface of the fetlock joint. Some breeds (especially heavy horses) have clearly defined streams of hair in a number of places: on the forehead, chest, underbelly, abdomen, etc.

Of the carpal, metacarpal and digital cushions on the paws of plantigrade predatory animals (bear) in horses, only the digital cushion has been well developed. The crumbs of other places of the hand and foot exist only as rudiments and receive special names. So, the metacarpal crumb is called a spur. It is located on the plantar (volar or plantar) surface of the 1st phalanx, hidden by tufts of long brush hairs and represents a rudimentary (from 2.5 cm or more) mass of horn columns and an intermediate horn. In light horses, the spurs are usually smaller than in heavy ones. Carpal, as well as tarsal crumbs are called chestnuts. On the thoracic limb, the chestnut lies medially above the carpal joint, and on the pelvic limb, it lies slightly below the tarsus on the medial surface of the metatarsus. The chestnut is similar in structure to a spur.

The digital crumb - pulvinus digitalis - performs the role of a mechanically acting elastic organ during gaits, in the region of the distal end of the finger (see finger mechanism). As an instrument of touch, it is already in many respects inferior to the crumbs of predatory, more primitive devices. Under the influence of the hoof, it took the form of a wedge bifurcated by a longitudinal groove, in which one can distinguish a wide thickened cushion of the crumb-torus pulvini.

Rice. 10 Horse thoracic finger

The end of the 4th metacarpal bone, 2- fetlock joint, 3- muscle branch to the tendon of the common digital flexor, 4- coronal joint, 5- hook part of the hoof, 6- tendon of the digital flexors, 7- interosseous muscle, 8- digital vein, 9- brush , 10 - position of the upper contour of the lateral cartilage, 11 - digital crumb with cartilage, 12 - calcaneal part of the hoof

The subcutaneous layer of the crumb is strongly changed in comparison with the subcutaneous layer of other places of the skin. In the crumb, it is adapted to the role of a spring, due to which it is distinguished by high density and elasticity. It contains significant bundles of adhesive fibers intertwined with a network of elastic and layers of adipose tissue. In the area of ​​the arrow, adipose tissue and elastic fibers decrease in quantity, as a result of which the skeleton of the arrow becomes harder and denser.

The subcutaneous layer of the crumb is generally wedge-shaped, and its slightly forked wide part is called the subcutaneous cushion of the crumb-pulvinus subcutaneus. It is nested between the lateral cartilages, which cover it from the sides. With its deep surface, the subcutaneous layer of the crumb is adjacent to the fascia of the deep digital flexor; at the same time, the pillow is suspended by a special ligament to the end of the tarsal bone. The pointed front part of the crumb is directed towards the sole and is called the subcutaneous arrow-furca subcutanea.

Rice. 11 Structure of the hoof

The lateral cartilages - cartilagines pulvinares - are a modification of the subcutaneous layer of the digital crumb, together with which they make up one original elastic device of the distal end of the finger. There are two lateral cartilages - lateral and medial. Each of them firmly adheres to the corresponding branch of the hoof-shaped bone, which is why it is usually described under the name of ungulate cartilage.

The umbilical, or hoofed, cartilage is an irregularly shaped cartilaginous plate; with its upper section, it protrudes under the skin over the hoof border on the lateral side and reaches almost half the height of the coronoid bone (Fig. 10-10). In front, the lateral cartilages reach the tendon of the common digital extensor, and behind they cover the pillow of the crumb and bend towards each other. Many vessels pass along the convex outer surface, some of which penetrate the cartilaginous plate in the lower and posterior sections. The concave inner surface covers the coronoid bone from the sides with its front section, and behind it is especially firmly fused with the crumb pillow. There are numerous grooves and channels for vessels on the border of the fusion. Occasionally (within one and a few percent) the ulnar cartilage undergoes ossification, especially in heavy horses.

The lateral cartilage is connected by a number of ligaments with neighboring bones: hoof-shaped, shuttle, coronary and even fetlock.

The basis of the skin of the crumb - corium pulvinare - has a developed papillary layer, but in general it does not represent anything characteristic. The part of this base, located in the area of ​​the arrow, can be called the base of the skin of the arrow - corium furcale (Fig. 12-10).

The producing layer of the epidermis forms a thick but soft stratum corneum within the crumb cushion. In the region of the arrow, the stratum corneum is especially massive, it is distinguished by great elasticity and forms the horny arrow of the crumb-furca cornea (Fig. 12-2, 3). It has the shape of a wedge and on the volar surface bears two legs of the arrow - crura furcae - and an interpeduncular groove - sulcus intercruralis. Opposite this furrow on the other side of the horn arrow is the crest of the arrow-spina furcae. The pointed end is called the top of the arrow - apex furcae. On the sides of the legs of the arrow there are lateral furrows, with which it borders on the neighboring parts of the hoof.

Fig.12 Horny hoof shoe from the plantar side (A); the basis of the skin of the hoof and the crumb on the same side (B)

stratum corneum of the crumb cushion, 2- horny arrow of the crumb, 3- legs of the arrow, 4'- branches of the horny sole, 5- white line, 6- plantar edge of the horny wall, 6'- lateral section, 6 "- medial section, 7- heel angles, 8 - hoops of the horny wall, 9 - base of the skin of the cushion of the crumb, 10 - base of the skin of the crumb frog, 11 - base of the skin of the hoop, 12 - base of the skin of the sole of the hoof

The epidermis of the digital crumb contains tubular glands curled in a glomerulus; they secrete a secret containing fat.

Hoof-ungula- (Fig. 9,10,11,12) is a derivative of the skin, transformed at the end of the finger into a hard skin tip; it corresponds to the claw of carnivores and the nail of primates (without crumb).

The hoof consists of: the horny layer of the hoof, which forms a highly developed horny shoe, or horn capsule, of the hoof; it consists of the horny wall of the hoof and the horny sole and bases of the skin of the hoof.

For convenience of description, the basis of the skin of the hoof is divided into the following sections: hoof border, hoof rim, hoof wall and hoof sole (Fig. 12, B-12).

The subcutaneous layer of the hoof - stratum subcutaneum ungulae - is very slightly developed and in its distribution is limited to the area of ​​​​the border and corolla, as well as the area of ​​\u200b\u200bcontact of the skin with the final segment of the tendon of the common digital extensor. This layer does not have any features and is a loose, irregular connective tissue rich in elastic fibers.

The basis of the skin of the hoof - corium ungulae - as a connective tissue lining for the epidermis is present everywhere. With its deepest, most dense part, the base, in places devoid of a subcutaneous layer, is directly and firmly fused with the periosteum of the bone. This part closest to the periosteum is called the periosteal layer. Such a connection takes place in the region of the hoof wall and the hoof sole, i.e., where there are neither tendons nor cartilage, but only the periosteum of the hoof-shaped bone is present.

At the base of the skin of the hoof, in addition to the periosteal layer, the reticular and papillary layers are pronounced. Abundant vessels branch in the reticular layer and there is the same venous network. This layer, due to the richness of the vessels, is rightfully called the vascular-stratum vasculare. Here, even the transition of some small arteries without branching to capillaries directly into veins is observed - arteriovenous anastomoses.

The papillary layer of the base of the skin is highly developed, very rich in capillaries and, as a result, acquires a bright red color. It is characterized by the fact that the papillae in some places are unusually long, as, for example, in the region of the hoofed corolla, while in others they are linear, that is, they form on the surface of the base of the skin a whole series of parallel scallops called leaflets.

When considering the epidermis, it is advisable to single out especially the producing and stratum corneum.

The producing, or deep, layer of the epidermis adjoins directly to the surface of the papillary layer of the base of the skin and repeats its location with its papillae and leaflets. Reproducing towards the surface, it gives the stratum corneum of the epidermis. Following the structure of the papillary layer of the skin base, the producing layer produces two types of horn: tubular and leafy.

The first type of keratinization more closely resembles the usual relationship between the papillae and the producing layer of the skin. It occurs where the producing layer covers very long papillae of the skin base in the form of conical caps. At the top of each cap, the cells extend in columns and produce a stratum corneum around them in the form of hard tubes. After the death of the centrally lying cells, the columns become hollow tubules. These tubules, together with the intertubular horn between them, make up the tubular horn.

The second type of keratinization is observed in places where the producing layer dresses the leaves of the skin base in the form of linear caps.

Cell caps produce between parallel connective tissue leaflets horny substance in the form of horny leaflets.

These horny leaflets are connected in one piece by a horny area that grows above the tops of the linear caps, forming together the leaflet horn.

The horn border, located at the transition from the skin of the finger to the hoof, significantly weakens the pressure of the upper edge of the horny hoof wall on the adjacent area of ​​hairy skin.

The hoofed corolla - corona ungulae - following the hoof border, also hugs the beginning of the hoof around, and behind it continues to the plantar side of the hoop parts of the wall, everywhere accompanying, therefore, the hoof wall as its proximal edge.

The base of the skin of the corolla - corium coronae - together with the underlying subcutaneous layer of the corolla - subcutis coronae - represents a clearly expressed connective tissue, highly elastic shaft 1-1.5 cm thick, separated from the base of the skin of the border by a narrow linear depression - coronal fold.

Ahead, this shaft is convex and wide, on the sides it becomes narrow and flat, and towards the crumb it drops completely and loses the character of the shaft. The papillary layer of the base of the corolla skin is characterized by particularly long (4-6 mm), relatively densely planted papillae, their tips directed distally, parallel to the hoof wall. At the border of the transition of the base of the skin of the corolla to the base of the skin, the walls of the papilla decrease, stacking in rows. In the direction backwards, the high papillae of the corolla can also be traced on the plantar side of the hoof along the frog, approximately to its middle, where they already pass into the papillae characteristic of the basis of the skin of the sole. The basis of the skin of the corolla is very rich in blood vessels, as well as nerve plexuses, which is why it serves as a real organ of touch. This organ mainly senses irregularities and the general character of the soil when stepped on by hard, insensitive horny parts of the hoof, the vibrations of which respond to the coronet. The producing layer of the epidermis dresses the papillary layer of the corolla skin base. It produces a thick mass of tubular horn that forms the coronal layer of the horny wall of the hoof.

Fig.13 Position of the lateral cartilage

1st phalanx, 2 - 2nd phalanx, 3 - 3rd phalanx, a - branch of the 3rd phalanx, b - lateral cartilage, c - hoof contour, d - crumb cushion, e - subcutaneous arrow

Hoof wall - paries ungulae - skin covering the back and sides of the 3rd phalanx of the finger. In the horse, the wall on each side makes a characteristic sharp turn at an acute angle on the sole from behind and continues on the last one. Here, the wall takes on the shape of a wedge on each side, i.e., it gradually decreases, without reaching part of the rim, the top of the arrow. This peculiar bending of the hoof wall occurred in the past due to the wedging of the crumb arrow into the sole area. Along the edges of the arrow, the wrapped wall continues, fading away. The angles of rotation are called the calcaneal angles of the wall, and the hoof wall extending from them to the sole is the bar wall. The overhand part is accompanied by the one who is bent here and also comes to naught.

The layers of the hoof wall are constructed as follows.

The basis of the skin of the wall - corium parietale - fuses with the periosteum of the coffin bone, dresses the latter from the dorsal and lateral surfaces, and from here it bends over the inversion angle to the sole and serves here as the basis for the skin of the inversion part. Thus, the subcutaneous layer is completely absent here. The basis of the skin of the wall has a very characteristic structure of the papillary layer. Instead of separate papillae, leaflets (combs) are developed here. Gradually rising, they go in the direction from the corolla to the free plantar edge of the coffin-shaped bone. In the latter, behind the inflection towards the sole, the scallops take the form of individual papillae and join the papillae of the base of the skin of the sole.

The leaflets of the base of the skin of the wall can be considered complex in the sense that small secondary, or additional, leaflets protrude on both sides of them, running in the same direction, i.e. along the long axis of the main leaflets (Fig. 15-B). The most densely leaflets are located on the hook (front) surface of the wall; here they are the highest, and towards the inversion part they decrease and become less frequent.

The producing layer of the epidermis produces the leaf horn. The latter, together with the coronal layer and glaze, forms the horny wall of the hoof.

The horny wall of the hoof - paries cornea - represents the outer, visible when the animal is standing, part of the horny capsule of the hoof. Near the crumb, it bends on both sides at an angle to the area of ​​the sole and stretches here parallel to the edges of the frog in the form of small wedges, in accordance with the location of the base of the skin of the collar (Fig. 12-8). The outer surface of the horny wall is convex and smooth, the inner surface is concave and equipped with horny leaves.

The thickness of the horny wall of the hoof as a whole consists of three horny layers: superficial-glaze, middle-coronal and deep-leaf

Glaze, or surface layer, -stratum tectorium (Fig. 14) - is pushed onto the wall from the side of the border in the form of a thin layer. It is clearly visible only in young animals, and with age it is erased and already loses the character of a uniform cover of the hoof wall. It consists of weakly keratinized flat cells.

Fig. 14 Scheme of the cross section of the hoof

A-base skin wall; B-its leaf layer; W-producing layer of the epidermis wall; G-leaf layer; D- supraleaf area of ​​the leaflet layer; E-crown layer of a tubular horn, cut across; J-glaze.

Coronal, or protective, layer-stratum coronarium, s. str. medium ungulae - the most massive, hardest and most durable in the horny wall. It is difficult to cut with a knife, almost does not swell in water (which is why it is called protective) and is built from a tubular horn, which is produced by the producing layer of the epidermis of the base of the corolla skin. The proximal (upper) edge of the coronoid layer bears the coronal groove; on its surface, point depressions (holes of horn tubes) are noticeable. The described layer is pigmented, and the dark color of the horn capsule depends on this. Only the deepest stratum corneum has no pigment and is softer. They are directly adjacent to the leaf layer and, together with the latter, participate in the formation of the white line. The growth of the coronal layer occurs from the coronal groove towards the plantar, free edge of the hoof wall.

The leaf layer - stratum lamellatum (Fig. 14-G, D) - develops from the producing layer of the epidermis, located on the leaflets of the base of the skin of the hoof wall. It is not pigmented, relatively soft, and forms horny leaflets located along the wall from the coronal groove to the plantar margin. They are placed in the intervals between the leaflets of the base and at the coronoid layer are connected by a superficial horny layer, which can be characterized as a supralamellar layer.

On the plantar margin, when viewed from the side of the sole, this layer, together with the deep layers of the protective layer, is clearly visible in the form of a white (slightly yellowish) strip along the circumference of the sole contour, called the white line, or leaflet zone-zona lamellata. The leaf layer is distributed, like the coronal layer, along the entire hoof wall and extends to the hoops. Here the leaves become gradually shorter and disappear towards the top. The hoof sole - solea ungulae - occupies the supporting surface of the hoof in the form of a slightly depressed skin plate with a cutout for the frog. It closes the tip on the plantar side between the frog and the plantar edge of the wall.

The basis of the skin of the sole - corium soleare - is directly connected with the periosteum of the plantar surface of the coffin bone, since there is no subcutaneous layer in the sole. Its rather long papillae are directed almost vertically to the plane of the sole, i.e., with their apices facing the soil, when the animal is standing.

The producing layer of the epidermis forms a horny mass called the horny solea cornea (Fig. 12-4). The latter has the appearance of a slightly concave horny plate, which lies in the horny shoe on its plantar side. From the area of ​​the crumb of the finger, the horn arrow of the crumb and the obturator parts of the horny wall are pushed into it. This circumstance gives reason to distinguish on the hoof sole the body adjacent to the side of the toe, and two plantar branches; the latter from the body go back parallel to the hoop and abut against the calcaneal corners of the hoof wall with their tops.

The horny sole develops from the producing layer covering the papillae of the base of the skin of the sole, and grows towards the plantar, free surface. Its horn is quite dense, but significantly inferior to the strength of the horn of the hoof wall. The most superficial layers become crumbly over time and particles fall off.

The highest point of the dome-shaped horn sole is located in the region of the top of the frog.

Sweat glands - glandulae sudoriferae - in their secreting departments are strongly curled with glomeruli. They are considerably common in horses, so that the latter perspire visibly and profusely over the entire surface of the skin in comparison with other animals. Their sweat contains a relatively large amount of dissolved protein and therefore can churn into foam, which, when dried, turns into a white coating. Close in structure to the sweat glands are the soft glands. Sebaceous glands - gland. sebaceae-alveolar structure, quite strongly developed in horses. The mammary glands, or udder, - uber (Fig. 15) - in horses are located between the hips in the form of an oblong round body, divided by a significant inter-nipple sagittal groove into two halves. Each half carries one conical nipple (b). The nipple at the top has two (anterior and posterior) openings, each leading to its own short nipple canal, behind which there is its own cistern in the thickness of the nipple. The secret is poured into the anterior and posterior tanks completely isolated from the posterior and anterior sections of each half of the udder, which gives the right to assume the presence in each of them of two independent milk mounds that have merged along the milk line, and the nipples may represent a merger of the pair into one complex formation on each side.

Fig. 15 Mammary glands of a mare (A); dogs, pigs (B); a - gland body, b - nipple

The skin of the udder is smooth, and only traces of delicate hairs are visible on it. It contains sebaceous and sweat glands both on the body and on the nipples. They are especially strongly developed in the hairless sagittal trough between the mounds. Smooth longitudinal and circular muscle fibers run through the thickness of the nipple wall.

Around the nipple canal, elastic tissue is highly developed, which plays the role of a sphincter.

General characteristics of the skin of birds

The upper, or outer, layer of the skin of birds, more or less keratinized, is characterized by a rather small thickness. Below it is the malpighian, or germ layer, consisting of cubic or cylindrical cells that retain the ability to divide. These two layers form the epithelial covering, or epidermis, which is characterized by a relatively smooth surface; thickening of the epidermis in the form of papillae, warts, etc. are relatively rare.

A characteristic derivative of the epidermis of birds, specific for this class of vertebrates, is plumage. This also includes the horny covers of the jaws, hind limbs, claws and spurs.

Under the epidermis is the actual skin, consisting of two layers: dense subepithelial and loose subcutaneous. The subepithelial layer of the skin is characterized by the presence of muscles in it. There are true skin muscles (smooth), moving individual feathers, and false skin muscles (striated), moving entire areas of the skin (pterylia). The latter received such a name because they are only an offshoot of skeletal muscles. A feature of the subepithelial layer of some areas of the skin where it is devoid of plumage (naked places or appendages on the head and neck of chickens) is its spongy structure and, at the same time, strong vascularization.

Great mobility of the skin of birds is provided by the loose structure of the subcutaneous layer. Fat deposits accumulate in this layer, forming a fatty layer, the development of which is subject to strong fluctuations depending on the type of bird, breed, age, sex, and especially the season of the year. The fat layer serves as an energy reserve consumed during periods of growth, reproduction, and molting. In waterfowl, other things being equal, it is more developed than in chickens. In hens of meat breeds, it is more developed than in hens of egg-laying breeds.

In the skin itself, there are numerous nerve endings reaching the border with the epidermis, as well as tactile bodies (they are especially strongly developed in bare skin areas); some species of birds have cavities associated with the air sac system.

The epidermis and its derivatives (feathers) serve as the site of pigment concentration.

Of the skin glands, only the coccygeal, or supratail, gland is well developed. It is usually bilobed, located above the last tail vertebrae, at the base of the tail feathers. The tubules of the gland are arranged radially and open into a paired or less commonly single reservoir. Further, there are excretory ducts directed towards the tail, opening in a nipple-like thickening of the skin, usually dressed in small brush-like feathers.

The secret of the coccygeal gland consists mainly of the product of fatty degeneration of tubular epithelial cells. It is excreted under the influence of a contraction of a special circular muscle or as a result of the pressure of the beak, with which the bird covers the nipple-like thickening of the skin. Drops of the secret impregnate brush feathers, then fall on the beak and with its help are distributed throughout the plumage.

The functional significance of such lubrication is great: the plumage becomes more elastic, therefore more durable, less permeable to water. The coccygeal gland is highly developed in waterfowl.

It is possible that vitamin D accumulates in the coccygeal gland. When this gland is removed, pathological changes are observed in chickens and ducklings, to a certain extent similar to rickets.

The upper and lower jaws of birds are covered with modified skin, the epidermal layer of which is more or less strongly thickened and keratinized. The combination of skin covers of the upper and lower halves of the beak is called ramfoteki. It consists of two main layers - the epidermis and the skin itself. The skin layer of ramfoteka is very thin and adheres tightly to the periosteum; the epidermis is relatively thick and includes, in addition to the usual ones, also a granular layer located above the malpighian layer. The cells of the granular layer are filled with keratohyalin, from which keratin of the superficial stratum corneum is formed. The thickness and degree of keratinization of the latter vary greatly, as a result of which the density of ramfoteka is subject to significant fluctuations. These differences are sometimes found on separate parts of the beak of the same bird. In chickens, the horny layer of the ramphotheca is more or less evenly developed: in ducks, as in other lamellar-billed animals, the denser parts along the edges and at the end of the beak (the so-called nail) are separated from each other by less dense, slightly keratinized areas. There is also a bare skin rim at the corners of the mouth.

The legs of birds, as a rule, are covered with skin with a highly developed horny scaly cover. Only in some cases, when the tarsus is completely feathered, these scales may be absent. The podoteka consists of individual shields of various sizes and shapes. These scutes are well developed in front on the tarsus and on the upper side of the fingers, except for the place of the folds, where the scutes are much smaller and less frequent. In waterfowl, the growths of blotches form swimming membranes.

The color of the podoteka is very diverse and is subject to age and seasonal changes. Various pigments of melanin and carotenoid nature take part in its formation.

Spurs are sharp horn formations sitting on a bone base. They are located on the back side of the lantern. Chicken spurs are secondary sexual characteristics; in females, they are poorly developed or completely absent.

The plumage protects the skin of birds from damage, helps maintain a constant body temperature, and is involved in creating the bearing surface of the wing and tail. The plumage gives the body of birds a streamlined shape, which is of great importance when flying, swimming, diving. The covering feathers of the ear act as a sound catcher, replacing the auricle missing in birds. Some feathers are so specialized that they functionally replace the oil gland.

There is no direct proportionality between the number of feathers and the body size of birds. Being subject to age, sex, individual fluctuations, the number of feathers is relatively constant for a given species.

A typical, fully developed feather can be imagined as a thin, slightly convex blade-fan -vexillum-, connected to the stem-scapus. The trunk is divided into two sections: the proximal, relatively short, hollow, rounded ochin-calamus- and the distal, filled with round cells, tetrahedral, bearing the fan-rod-rachis. The lower part of the ovary is placed in the skin and is connected to the feather papilla, which enters it through the so-called lower navel-umbilicus inferior. Another hole in the developed pen, closing the so-called upper navel - umbilicus superior - is located at the base of the rod, on its lower side, at the beginning of the groove present here. From the upper navel, which is preserved in the formed feather in the form of a recess, a side trunk often departs - hyporachis - with a downy or semi-downy fan.

Fig.16. The structure of the contour pen. 1. downy part of the fan, 2- side rod, 3- feather bow.

The structure of the fan of a typical feather is presented in the following form. On both sides of the rod at a certain angle, symmetrically located flexible horny plates-beards of the first order -rami- depart, from which, in turn, rays extend, or second-order beards -radii. On the latter, grooves of the third order are placed - cilia -ciliae- or hooks -hamuli. Beards consist of an outer stratum corneum and an inner medulla formed by keratinized cell remnants with the inclusion of air bubbles.

The structure of the rays is varied: in the proximal part of the vane they are soft, downy, in the distal part they are flat and hard. Downy rays are like a chain of elongated cells connected by nodes. Solid rays carry hooks or have grooves instead. The hooks of some rays cling to the grooves of others, resulting in a dense, elastic fan. The grown feather is a dead formation that has lost its physiological connection with the body, however, the features of its structure are primarily of functional significance. In accordance with the variety of functions, the structure of feathers is diverse. The main types of structures differ mainly in the features of the connection of the elements of the fan.

Contour feathers have a hard elastic trunk and a dense elastic fan in the distal part. Contour feathers include coverts, flight feathers and tail feathers.

Cover feathers are usually somewhat convex and overlap tightly. They differ depending on the topographic location. On the dorsal side of the body, these include crown coverts, necks, backs, shoulder, supracaudal, and upper tail coverts.

On the ventral side of the body there are covering feathers of the crop, chest, abdomen, etc., and the tail feathers are covered with undertail. The lower leg coverts are sometimes elongated and in this case are called pants.

The covering feathers of the wing are divided into three types: the covering bases of the flight feathers are called greater wing coverts, above them there is a row of middle wing coverts, and above the middle ones there are several rows of lesser coverts. Small marginal coverts are located along the anterior margin of the wing.

The coverts of the ventral side of the wing-underwing are divided into the same groups as the upper wing coverts, that is, large, medium and small. At the same time, large and medium coverts are located in such a way that their upper (morphologically) side facing the skin. This is due to the fact that in embryogenesis they are initially formed on the dorsal side and only then move to the ventral surface of the wing.

Flight feathers are long hard feathers attached to the carpal section of the wing and forearm. The flywheels, sitting on the bones of the second and third fingers and on the carpal-metacarpal bones, are called large, or primary. The number of primary primaries is relatively small - 10-12. Structural features of the primaries are a strongly developed, strong, asymmetrical fan.

Rice. 17. Scheme of pen development

Epitrichium; 2 - malpighian layer; 3 - stratum corneum; 4 - pulp; 5 - skin layer of cells; b - annular sheath of the papilla; 7 - beard; 8 - pen rod; U - horn case. A - one of the first stages in the development of the pen; B and C are the next stages of pen development.

Flight feathers with a symmetrical fan, attached to the dorsal side of the ulna, are called small, or secondary. Their number fluctuates. They are structurally and functionally approached by the posterior shoulder; they are called tertiary primaries.

The tail feathers form the bird's tail; they are arranged in one, usually somewhat arched, transverse row attached to the pygostyle. The number of tail feathers (10-12) usually corresponds to the number of vertebrae (two feathers per vertebra). Sometimes tail feathers are from 8 to 24 or more (for example, in peacock pigeons). The feather of chickens is different from the feather of ducks and geese. It is longer and, with a somewhat shortened head, has a relatively elongated fan. The downy part of the fan is strongly developed. There are also differences in structure.

Along with the difference in the morphological and microscopic structure of the feather, there are also differences in its specific gravity. The specific gravity of chicken feathers is 0.57, ducks -0.42-0.44, geese -0.36.

The lightest contour feathers are in geese, and the heaviest in chickens.

Down feathers differ from contour feathers in the weak connection of the elements of the fan; however, in detail, the structure of down feathers varies greatly. These variations are largely related to age characteristics. The body of chicks (most birds) is covered to a greater or lesser extent with embryonic down, which can be in the form of a separate beard or a group of beards on a short, underdeveloped rod in the form of a loose feather with a short soft trunk.

The down of adult birds is usually hidden under contour feathers. The function of down is to retain body heat.

Powder down is a formation that releases the smallest horny grains that easily absorb moisture and, as a result, protect birds from getting wet. The structure of these feathers is very diverse. In a typical case, these are loose feathers with constant growth, disintegrating into powder as the horn sheath bursts. In more rare cases, this is ordinary fluff, which is characterized by slow growth. Powder down is present, in particular, in pigeons. It forms clusters located on the sides or in the rump. Functionally, it replaces the coccygeal gland.

Thread-like, or filamentous, feathers with a soft hair-like trunk and an extremely poorly developed fan (several short bare beards) are usually placed in groups (from 2 to 10) around contour or down feathers. They are relatively rare.

The bristles are feathers that consist only of a stem. They are usually placed at the base of the beak, sometimes on the toes, in rare cases above the eye, like eyelashes; tactile bodies often located at base of setae.

The uniform distribution of plumage throughout the body is characteristic only of flightless bird species (ratites). In all other birds, feathers are unevenly distributed only on certain areas of the skin - pterylia, between which lie bare, featherless areas - apteria. Feathers are located on pterylia with greater or lesser density, in a checkerboard pattern. This only applies to contour pens.

Rice. 17. Pterylia and apteria of chicken.

Pterylia are indicated by dotted lines.

Down sometimes evenly covers the entire surface of the body, for example, in ducks. Sometimes it is located only along the pterylia or only along the apteria, forming the so-called downy spots.

Feather development begins in the embryonic period. In a chicken embryo, on the 6-7th day of incubation, bookmarks of the primary (embryonic) down appear. The contour plumage of chickens also begins to develop in the embryonic period, and chickens hatch with partially developed flight feathers. The covering feathers of the body of chickens of fast-feathering breeds (leggorn) on some pterylia begin to grow already in the first days after hatching, in slow-feathering breeds (Rhode Island, Plymouth Rock, etc.), this process is two weeks or more late. The downy outfit of waterfowl (geese, ducks) begins to change to the first contour plumage at the age of one month (Beijing, Indian runners), and in ducks of other breeds (khaki-camibell) 10-15 days later. It is characteristic that in ducks the covering feathers of the body and fly feathers develop at different times (with a monthly interval), in geese this interval is much less.

At the moment of the most intensive development of plumage, when there is an increased differentiation of feather plates, the energy of the general growth of a young bird. The intensity of the overall growth of 12-day-old pigeons, when the plumage is intensively developed, is almost halved. The development of contour feathers during the seasonal molting of adult birds proceeds in general similarly to the process of the initial formation of the contour plumage of growing birds. The only difference is that in the first case, papillae are activated, sitting at the base of the contour feathers of the previous generation. There are some features in the development of feathers during the seasonal change of outfit.

A characteristic feature of the plumage of adult birds is its ability to regenerate, that is, the ability of feather papillae to become active not only during normal seasonal molting, but also after artificial plucking of feathers. It takes less time to restore a plucked feather before a normal molt than after it ends. The restoration of the feather is especially slowed down when not fully developed feathers are plucked. This reduces the size of the newly formed feathers. The speed of regeneration also depends on the number of simultaneously regenerating feathers: the more feathers there are (up to a certain limit), the earlier their growth ends. An essential role in the regenerative growth of the feather is played by nutritional factors, especially proteins, minerals, and vitamins. With B-avitaminosis, the growth of feathers stops. Feather growth also depends on the state of the nervous and endocrine systems.

The color of bird feathers is determined by the presence of certain pigments in them and a certain structure of the feather. Accordingly, in the color of the plumage, colors are distinguished: chemical, or absorption (pigment), objective structural and subjective (prismatic) structural. Pigments, in turn, are divided into melanins and lipochromes (carotenoids).

The structure of the skin of fur-bearing animals

The skin is conditionally divided into several parts, each of which has its own name. The need for division is caused by their unequal value and their different purposes in furriery production, and it also facilitates the description of the commodity properties of the skins, their defects and processing techniques. Skin and skin derivatives - hair - together represent the skin of a fur-bearing animal.

The skin of fur animals consists of: the skin itself (epidermis, dermis, muscle layer and subcutaneous tissue), hair, glands (sweat, sebaceous, milky), claws.

Nerves and endings and passing blood vessels are located directly in the skin.

The skin, in direct contact with the external environment, performs numerous and varied vital functions: the skin protects the body from mechanical influences and injuries, the epidermis prevents moisture loss and prevents the penetration of various substances and microorganisms into the body. The hairline and subcutaneous tissue provide thermal insulation, and the blood vessels and sweat glands provide heat transfer to the body. The skin is involved in metabolism, its subcutaneous tissue is a pantry of fat.

Epidermis - is a layered, keratinized epithelium on the outside. The epidermis is most developed on hairless areas of the body, for example, on the soles of the paws. The somatic cells of the epidermis are constantly moving, undergoing structural and chemical changes.

Dermis - located under the epidermis and is divided into two layers - the upper papillary and deeper reticular. The dermis is made up of connective tissue and contains collagen, reticulin, and elastin fibers. The strength of the skin is determined by collagen fibers, they are located along the length of the skin (from head to tail) and are interconnected more firmly than bundles running in the transverse direction, so the skin is torn more easily along than across. When sewing up holes, one must take into account the fact that the hole is spreading vertically, that is, towards the head and tail, and not to the sides. Elastin fibers have a branched shape, forming a network, and have properties such as elasticity, elasticity and extensibility. When drying, the elastin fibers shrink, therefore, to shape the skin and dry it evenly, it is dried on the rule. When the dried skin is moistened, the elastin fibers restore their properties.

In the dermis lie the root sheaths of hair, sweat and sebaceous glands, pigment cells. The sebaceous glands are alveolar in structure, and holocrine in nature, i.e. to those in which the secreting cells degenerate into a secret. The secret of the sebaceous glands - sebum - envelops the hair, protects it from the adverse effects of the external environment. The number, shape and size of the sebaceous glands are related to the degree of development of the hair roots and the density of their location. Thick roots have two large glands, thin roots have one, and some of the downy fibers have no glands at all. The secret of the sebaceous glands gives softness and enhances the shine of the hair. Sweat glands are involved in water-salt metabolism.

A mixture of secretions of the sebaceous and sweat glands forms grease, which creates lubrication of the epidermis, contributes to a better preservation of the physico-chemical properties of wool. The muscular layer is located below the dermis and is formed by striated tissue. When the temperature drops, the muscle layer contracts, and the skin gathers in folds, thereby reducing heat transfer.

Subcutaneous tissue is the link between the animal's body and the dermis. The subcutaneous tissue is more firmly bound to the skin than to the muscles, due to which the skin is easily separated during shooting, while the bulk of the subcutaneous tissue with subcutaneous fat is separated along with the skin. The laying of hairs occurs in the embryonic period by invagination of the malpighian layer of the epidermis into the skin. These invaginations in the pilar layer of the skin form vesicles (follicles). From the cells of the dermis, ingrown into the base of the hair follicle, a papilla is formed, which is well supplied with blood vessels and serves as a nutritional organ for the hair. Simultaneously with the follicle, sebaceous, sweat glands and a hair muscle lifter appear. By active division, a bulb is formed around the papilla. The cell mass of the bulb is pushed up along the hair sheath and hardens at this time, i.e. becomes keratinized.

1 Structure, hair coloring

The hair that forms the hairline of fur-bearing animals is distinguished by shape, size, structure and color. Hair is a keratinized thread of the skin tissue, and consists of two parts: a rod protruding above the surface of the skin tissue and a root located in the dermis immersed in the hair sheath.

Hair in relation to the skin tissue is in an inclined position. The general principle of the direction of the hair rods is from the head of the animal to the tail, including on the ridge - from the head to the sacrum, on the sides - somewhat downward. The pubescence with this direction of the hair experiences less friction and does not fall off.

The hair shaft has three layers: scaly (cuticle), cortical and core: the scaly layer of the hair protects the cortical from the external environment; the cortical layer forms the walls of the central channel of the hair, the strength of the hair to break depends on this layer, it contains a dye (pigment) that determines the color of the hair; the core layer has a loose structure and consists of shriveled irregularly shaped cells containing pigment; the thermal conductivity of the hair depends on the development of the core layer in length and width. The wider it is, the warmer the skin of the beast. By the thickness of the core and cortical layers, it is possible to determine to which animal the hair under study belongs.

All hair colors (except white) are determined by one pigment - melanin. The difference in colors with different shades is due to the different degree of oxidation of the pigment, as well as its thickness, quantity, shape and size of the granules. The hair root ends with a thickening - a bulb, which is connected to the skin through the hair papilla. The bulb consists of living cells, due to which the hair shaft grows. The hair root lies in a hair bag formed by the skin, and is somewhat oblique, which determines a certain direction of hair growth on the skin. Amino acids containing sulfur (methionine, cystine, etc.) play a very important role in the growth and development of hair. One of the remarkable properties of natural fur is the complex natural color of the hairline, unevenly distributed over the area of ​​\u200b\u200bthe skin and deep into the hair zones. Achromatic shades are observed in areas of hair of the skins of arctic fox, silver - black fox; chromatic - red foxes, black - brown, muskrat, raccoon. The assessment of color zoning is carried out according to the longitudinal and cross sections of the skin according to two indicators: the lengths of the color sections of the hair and the color characteristics of these sections.

The guard hair has three color areas:

) light brown, light gray (lower);

a) dark brown (medium);

) light brown tips (veil).

The length of the upper section is the most stable in terms of the area of ​​the skin and is 2-3 mm; the length of the middle section has the greatest value in the region of the nape of 8-12 mm and the smallest in the regions of the rump and the lower back of 3-6 mm; the length of the lower section is 7-12 mm, reaching its maximum value along the ridge line. According to the color of the hairline, the skins of fur-bearing animals are divided into several groups or categories, the description of which is given in the standards. The division of skins into color categories is provided for the following types:

sable - 7 colors;

mink - 14;

silver-black fox - 3;

blue fox - 3;

nutria - 7.

Skin prices fluctuate to a very large extent depending on the color.

The total length of the down hair over the area of ​​the muskrat skin varies from 10 to 15 mm, the length of the upper and lower down zones throughout the entire skin are related to each other approximately as 1:5 - 1:4. The color of the outer hair zones of the muskrat varies from light brown and light gray on the belly to darker and more saturated shades of brown in the ridge area. The coloration of the zones of the downy hair of the muskrat is almost uniform over the area of ​​the skin. A darker shade of zones 1 and 2 is found in the central lower part of the skins.

The guard hairs of the red fox have 2 - 3 differently colored color areas: dark gray at the base, light gray and red, downy hairs are colored uniformly along the length and have a gray tint. In the region of the ridge, along the length of the guard hairs, three sections are distinguished, on the side and belly of the skins of the red fox, the guard has two sections - gray at the base and red tips. The length of the upper section averages 3-8 mm, the middle 10-40, and the lower 18-40 mm. The hue of the upper section of the awn is characterized by a minimum value of brightness along the ridge line, increasing towards the belly. In the area of ​​the shoulder blades along the side line, the upper section of the hair has a slightly saturated light red tint. Along the line of the belly in the area of ​​​​the flanks are the most light gray, pale yellow areas. The lower section of the guard hairs has a gray tint, the brightness of which decreases towards the rump and increases towards the rump. Darker down is located along the line of the ridge, lighter in the area of ​​\u200b\u200bthe belly and flanks. The length of the downy hair varies almost in the same way as the length of the lower section of the guard hairs.

For most nutria, a dark brown color is characteristic; very dark brown and brown ones are found. Part of the hair is fully pigmented, and the light part of the granny is clarified in part. The underfur is brown, of varying intensity. The abdomen is lighter in comparison with the ridge. Undesirable yellow, orange, brown and reddish shades in color.

For the hairline of the skin of a silver-black fox, the colors are characteristic:

black or dark, with a well-pronounced pure white silver, as well as pure light silver;

hairline, as in the skins of the first color, but with a slight brown tint, downy hair is dark gray or gray;

dark brown or light silver without a veil or light silver with a brownish tint, downy hair dark gray or light gray.

Mink skins of cellular breeding according to the color of the hairline are divided into:

black or almost black over the entire area of ​​​​the skin, the down is dark gray with a bluish tint;

dark brown or brown, down dark gray or gray - blue with a brown tint;

covering and downy hair of blue color of varying intensity;

beige - smoky with a pronounced blue tint, the fluff is pure pale blue, on various parts of the skin there are gray covering hairs, in harmony with the general tone of color;

pale brownish - smoky with a pink tint, the down is white with a bluish tint, etc. The guard hairs of the arctic fox have three differently colored areas: white at the base, light gray middle and dark gray tips (veil). The lengths of the middle section of the hair have a maximum value on the nape and shoulder area - the "cross" (25-30 and 7-12 mm, respectively) and decreases towards the middle of the skin. The length of the hair of the white section decreases towards the "cross" (up to 18 mm), gradually increasing towards the rump (36-42 mm). The downy hair of the arctic fox has a gray tint, the lightness of which increases in the region of the belly.

Experimental data on the zonal coloration of the hairline of the studied types of fur made it possible to draw the following conclusions:

there is a relationship between the total length of the hair and the lengths of the color areas - as a rule, the nature of their change coincides; the topography of the change in the lengths of the color areas depends on belonging to a certain type along the length of the hairline.

The hairline of the muskrat, which belongs to the medium-haired types of fur, is characterized by an increase in the total length of the hair and individual sections along the ridge line, and especially in the rump.

For long-haired species (red fox and arctic fox), the opposite picture is characteristic - the presence of "dips" along the ridge, an increase in the length of the color areas of the hair towards the sides and belly.

The coloring of the color areas of natural fur includes various shades of brown, gray - blue and gray. The color of the skin by area is determined, as a rule, by the color of the middle zone of the awn and the upper zone of the fluff, on which the color of the "veil" is superimposed, the intensity of which varies depending on the length of the upper section of the awn. The color of the downy hair is, as a rule, more uniform than that of the awn and varies little over the area of ​​the skin. The presence of heterogeneously colored areas along the length of the hair makes it possible to create a variety of color effects on the surface of the skins and by cutting the hairline to different heights. Local shearing in some areas can significantly change the appearance of the skin and get almost new fur with an unusual color topography. All this expands the design possibilities of fur products and is one of the ways to remove hairline defects.

The shape of the hair is divided into conical, cylindrical, spindle-shaped and lanceolate. In addition, hair can be divided into several categories:

sensory or tactile (vibrissae) - they are thicker, elastic, have a conical shape and are located mainly on the front of the body, there are many of them on the head. Vibrissae are associated with nerve branches and therefore have a high sensitivity;

guide hairs are predominantly spindle-shaped, they are longer and thicker than hair of other categories, of a single color, their tips rise above the entire hairline, forming a "veil"; guide hairs are rare, but give the skin a beautiful appearance, enhancing its splendor; the most characteristic feature of the guide hair is the shape of its tip, which gradually becomes thinner;

the guard hairs are on average shorter and thinner than the guide hairs, their shape is lanceolate, the color can be uniform, multi-colored and zonal, the main tone of the skin color depends on it, the guard hairs are much larger than the guide hairs, they have an oblique, almost horizontal bend, which allows them to reliably cover and protect the underfur. Guard hairs play a leading role in the formation of the hairline and its resistance to matting;

downy hairs make up the bulk of the pubescence - they are divided into intermediate and actually downy hairs - these are the thinnest and shortest cylindrical hairs with a well-developed core layer, downy hairs are always crimped along their entire length, their color is usually monophonic.

3 Location of hair on the skin

The hairline of fur-bearing animals has a tiered structure.

Downy hair, which is shorter, thinner and more delicate than other types of hair, forms the lower, densest tier of the hairline; guard hairs are thicker, resilient and longer than downy hairs, they form a medium, less dense tier; guide hair - the longest, thickest and most elastic - create an upper, rarer tier. This arrangement of thick and thin hair makes the hairline elastic. The outer and guide hairs, forming the upper tiers, cover the layer of intermediate and downy hairs, as if protecting the hairline, therefore they are called coverts. The roots of the guiding hairs lie deeper in the dermis than the guard hairs, and the roots of the guard hairs, in turn, are deeper than the downy ones. The hair roots in the thickness of the skin of fur-bearing animals on the back are located obliquely in the direction from the head to the tail, therefore, the hair shafts on the surface of the skin have mainly the same direction.

Hygiene care for the skin and horns of farm animals

The hygiene of farm animals is the basis of prevention, the science of protecting and strengthening the health of animals, increasing natural resistance by rational methods of growing, caring, keeping and feeding, in which animals show high resistance to diseases and give maximum productivity due to heredity.

Along with the hygiene of watering, feeding and keeping animals, hygienic measures for caring for them are important. Systematic care of animals is an indispensable condition for maintaining their health and high productivity. In the absence or with insufficient and irrational care of animals, the effectiveness of the best feeding and good premises is significantly reduced, as well as the productivity and quality of the products obtained.

1 Skin care

The skin is filled with tiny blood vessels, which expand in warm weather and thus allow a large amount of heat to pass through, and contract in cold weather and therefore help retain heat in the body. Further, there are pores in the skin that allow sweat and fat to pass through. Sweat is released through the pores when there is excess heat inside the body. Fat is secreted through the pores, making the skin soft and the coat smooth and shiny. In addition, the skin, like the lungs, inhales oxygen and releases carbon dioxide from the body, although to a lesser extent than the lungs. As you can see, the skin contributes to the normal course of life throughout the body, and therefore the correct administration of their duties by other organs of the body is possible only if the skin is intact, unharmed and correctly performs its functions.

Skin cleaning is used in all animals except sheep.

It is necessary to wash and clean the animal, firstly, in order to clean it of dust and dirt adhering to the coat and skin. Secondly, by washing and scratching, the skin is cleansed of unnecessary waste that has appeared from the evaporation of sweat and fat from the skin.

Cleaning animals with brushes; in addition, when cleaning, combers are used, which serve to clean the brush from dirt and wool adhering to it. However, every animal needs skillful cleaning. For example, it is impossible to clean horses and cows with the same methods. In general, cleaning animals with a metal comb with sharp teeth is harmful. When cleaning with a comb, we notice that the animal is restless, and, therefore, such cleaning is unpleasant for him. Animals with delicate skin are especially worried. Therefore, combing can be allowed in animals with coarser skin. Vacuum cleaners are also used for cleaning. The specified set must be assigned to individual animals or a group of them served by one person. Cleaning inventory is stored in a special locker in numbered nests and subjected to periodic disinfection in hot lye, creolin solution, etc.

Livestock cleaning is best done daily, but at least once a week. The cleaning of dairy cattle is paid for with the best milk yields.

Animals are cleaned before feeding, cows no later than 1 hour before milking, as care during feeding disturbs them and leads to poor feed intake. In the process of work, a large amount of dust and microorganisms are released into the air, so it must be carried out outdoors - horses at the hitching post, cows in pens or milking areas, pigs in the walking yards.

In rainy and inclement weather, with strong winds, in winter with frosts above 15 0С, it is better to clean animals indoors (in arenas, vestibules, passages). At the same time, ventilation pipes and windows are opened (on one side), preventing drafts.

Cleaning usually begins on the left side of the animal. Consistently clean the head, neck, forelimb and torso, then move on to the croup and hind limb. Do the same on the right side. The brush is periodically (after four strokes) cleaned on the comb; from time to time, the dirt accumulating on the comb is knocked out on the deck away from the animal.

The second stage of skin cleansing is to remove fine dandruff dust. To do this, the skin is wiped with a clean, damp cloth, which must be washed frequently in water and wrung out. After that, they proceed to the last, third stage - the hair is wiped with a well-wrung cloth. This is done along the course of the coat to smooth the hairline and give it shine. The mane, bangs and tail of the horse are cleaned with a brush and cloth, tangled hair is sorted out with hands. Close attention should be paid to the cleanliness of the limbs most prone to contamination.

The natural openings of the body, as well as the eyes and nostrils, should be washed outside with water and wiped dry with a cloth or sponge.

On the skin of gray horses lying on a dirty litter, yellow spots form, sometimes not amenable to a brush and a comb. In such cases, contaminated and stained areas are washed off with warm soapy water, sometimes using charcoal gruel for bleaching.

Horse skin care is necessary to improve its performance, skin and body resistance to external influences and various diseases.

Cleaning the skin of cattle has, in addition to a direct effect on the body, also a general preventive value. A huge number of microorganisms are found on the skin and wool of cows, which, getting into the air, can infect milk, surrounding objects, feed, and sometimes animals. With the right sanitary and hygienic content, cow's milk is twice as less contaminated with microorganisms. In order to obtain pure milk, before each milking, it is necessary to wash the udder, tail, contaminated limbs and wipe them down.

To increase the productivity of grooms, milkmaids and other livestock workers, mechanized methods of skin cleaning have been developed and are being introduced into production. They can be carried out using the vacuum of the milking machine and a manual or mobile electric vacuum cleaner. In the first case, a rubber hose is put on the pipeline crane (as in milking), the other end of which is connected to a bucket of a milking machine converted for this purpose. A second, wider hose departs from the bucket, at its end there is a comb tube. The comb is carried out over the wool and against it. At the same time, along with the air, dust, dandruff, food residues and fallen hair are sucked in, polluting the skin. When using a vacuum cleaner, special metal hollow combs are attached to a flexible hose instead of ordinary brushes. All possible contaminants sucked in by a vacuum cleaner from the skin are collected in a cloth dust collector mounted in the lower part of the device. To clean the skin, the comb is turned with the teeth down and lightly pressed against the wool with the toothed groove. It is enough to spend 2-3 times on one place of the skin. It usually takes 3-5 minutes to clean one cow, and 7-8 minutes to clean a horse.

Pneumatic cleaning of animals increases labor productivity by 4-5 times, it is hygienic, it can be used indoors at any time of the year and in any weather. The animal gets used to it very quickly. Dust, dandruff, microorganisms and loose hair are not sprayed, do not pollute the room air, but are transferred to the filter, where they accumulate and are then removed.

Washing and bathing animals contributes to the mechanical cleaning of the skin from dirt and sweat. During washing, mineral salts deposited on the hair dissolve, skin receptors are irritated. Cool water refreshes animals in hot weather, increases heat transfer through the skin, reduces lethargy and muscle fatigue, increases vigor and efficiency. As a result of washing or bathing, heat production, resistance to temperature changes increase, appetite improves and the body hardens.

The most contaminated parts of the body, spots, limbs, external genitalia, tail and udder of cattle are washed with warm water and soap; in horses - dried mud, lower parts of the legs, tail, mane, scrotum. Then be sure to wipe dry with a straw bundle or rags to prevent the body from cooling.

As a skin care technique, general washing of animals is of great hygienic importance, which cannot be carried out at low temperatures, drafts and high humidity. The water temperature for washing animals should be at least 300C. After the water procedure, the skin is rubbed, dried, valuable animals are covered with blankets, they are brought into stalls with dry plentiful bedding. Manual washing of animals is a laborious process, so a shower or brush-shower is recommended. For mechanized washing, you can use mobile de-installation units (DUK, LSD-2, VDM).

In summer, it is useful to bathe animals in the morning and in the evening at a water temperature of at least 18-20 0C for 10-15 minutes. Cool water is a powerful means of excitation, restructuring of the body and increasing overall tone. The reservoir should be with running clean water. Animals are usually bathed 1-1.5 hours before feeding; hot work or sweaty, as well as the sick can not be bathed. For pigs, pens are often equipped near the farm or in the camp with a platform on which the animals are washed with a hose with a low jet pressure or bathing pools with replaceable water are arranged.

It has been established that bathing cows in the hot months of the year is economically beneficial - the fat content in milk increases markedly, milk yield increases by 0.77-0.85 liters per day.

When caring for cows, the focus should be on udder care and proper milking. Poor care and improper milking of cows can lead to udder diseases and reduced milk yields. The complex of veterinary and zoohygienic measures for the maintenance and care of dairy cows strictly provides for washing the udder before milking and the use of lubricants for teats. By conducting a pre-milking toilet, the number of microbes on the surface of the mammary gland and the likelihood of their getting into milk during milking are reduced, and the transfer of pathogenic microbes from sick animals to healthy ones is prevented. Sanitization of the udder before milking also causes milk flow - milk allowance. Bathing sheep for hygienic purposes is not performed. Their wool is highly saturated with water and it takes at least a day to dry a coarse-haired breed, and 3 to 4 days for merinos. Sheep are bathed either for economic purposes before shearing in order to get cleaner wool, or more often with treatment and prophylaxis - in case of scabies (anti-scabies baths). Naturally, you can bathe them for economic purposes in dry and hot weather.

In cattle, it is necessary to clean not only the body, but also the tail, because the animal will soon stain its body with a dirty tail. In addition, it must be remembered that the tail serves as a continuation of the dorsal spinal column, in which many nerves converge.

Brushes and combs should be washed from time to time with hot water and soap and treated with a disinfectant solution.

Pets should not be cleaned indoors. This leads to the appearance of a large amount of dust in the indoor air, which is harmful to animals.

Covering animals with blankets to protect them from the cold or insects is also one of the methods of skin care. Blankets cover mainly horses and, as an exception, cows. They are mainly used in cold weather, if the animals are left outside or in a cold stable after returning from work, and also after washing.

The best blankets are woolen, they are less thermally conductive and absorbent than linen ones. In addition, wool blankets dry out more slowly and absorb heat to evaporate moisture and do not stick to the body. In summer, it is better to use linen and cotton blankets, and during the mass summer of insects - mesh.

2 Horn care

An essential condition for the transfer of animal husbandry to an industrial basis is the creation of large complexes with a high level of mechanization of production processes, a large concentration of animals in limited areas.

This technology of animal husbandry, with all its positive features, has caused the emergence of massive surgical diseases, one of them is injuries caused by sharp horns of animals, which causes considerable economic damage.

The pathogenic effect of trauma on the animal organism has a number of features, the essence of which is as follows.

First, in acute cases, trauma may be accompanied by an immediate danger to the life of the animal due to damage to vital tissues and organs, bleeding, etc.

Secondly, with extensive closed tissue damage and intensive absorption of tissue decay products, traumatic toxicosis of animals often occurs.

Thirdly, with injuries caused by a strong impact of a mechanical factor, rupture of internal organs (liver, stomach, intestines, bladder, etc.) can occur.

Fourthly, when pathogenic microbes penetrate into injured tissues, injuries are often complicated by abscesses, phlegmon, necrobacteriosis, actinomycosis, etc.

Fifth, in a number of cases, injured animals develop neurotrophic disorders in the form of paresis, paralysis, and atrophy, which significantly worsen the general condition of the injured animal.

A large number of injuries in large-group keeping of animals is caused by horns. Therefore, the task of farm veterinarians is to create polled herds. It would be advisable to have hornless breeds of cattle, but this is quite difficult. Easier to dehorn livestock. Thus, antlers are usually amputated to prevent injury in free-range livestock. Indications for amputation of the horns may also be their incorrect growth, fractures and neoplasms of the horns, and the vigor of the animal.

The operated animal is fixed in a standing position by applying nasal forceps. For more reliable fixation, the head of the animal should be tied to a pole, but it must be borne in mind that especially restless animals can break the horns.

Antipsychotics are administered to especially excitable animals in order to calm them down 15-20 minutes before the start of fixation.

Tools needed for the operation: scalpel, hooks or surgical tweezers, sheet or arc saw. In addition, a syringe with a short injection needle, surgical needles, a needle holder, silk for ligatures and sutures, sterile swabs, bandages, a sterile sheet or oilcloth are needed.

Of the medicines, 30 ml of a 3% solution of novocaine, a 0.5% solution of ammonia, a 5% solution of iodine, and an antibiotic for treating a wound are required.

The preparation of the surgical field is carried out in four stages: mechanical cleaning, degreasing, treatment with an antiseptic, isolation of the operation field. Mechanical cleaning includes washing with soap and shaving. Degreasing of the surgical field is carried out with a sterile gauze swab soaked in a 0.5% solution of ammonia for 1-2 minutes. The fat-free operation field is treated with an antiseptic according to the Filonchikov-Grossich method. Its essence lies in the fact that the fat-free field is "tanned" and aseptic with a 5% iodine solution, first after mechanical cleaning, and then immediately before the incision. In this case, the interval between treatments should be at least 5 minutes. The treatment of the surgical field with an antiseptic begins from the center (incision site) to the periphery. The operation field is isolated using sterile sheets or oilcloths.

The operated animal is fixed in a standing position. An operating field is prepared around the horn for 7-10 cm. The corresponding nerves are blocked and 8-10 minutes after the administration of the anesthetic solution, the operation is started.

First, the skin is cut along the outer edge of the frontal crest, starting from the base of the horn and continuing 5-7 cm in the direction of the mouth (orally). Then, expanding the edges of the wound with hooks or surgical tweezers, they look for the neurovascular bundle of the horn, where the artery and vein are separated and ligatures are applied to them. After that, the skin is cut along the occipital crest, starting from the base of the horn and continuing 3-6 cm towards the sagittal line. In the future, both wounds are interconnected by a circular incision. It is led around the base of the horn, along the upper border of the hairy skin. Next, the skin is separated from the underlying tissues in the frontal region 3-5 cm from the edges of the wound and 5-6 cm near the frontal crest. The resulting skin flaps are turned away with wound hooks (tweezers). Then, with a sheet or arc saw, the horn is completely cut off, slightly capturing the frontal bone.

After that, the wound is thoroughly cleaned of bone sawdust and blood clots with a sterile swab, the skin edges of the wound are brought together and knotted sutures are applied along the edges of straight incisions, and a horizontal loop-shaped suture is placed in the center at the level of the former horn. Before suturing to prevent infection, the wound is treated with antibiotic powder. The bandage is not applied, the sutures are removed on the 10th day.

With the described method of dehorning, even in the first days after the operation, there are no significant deviations in the state of the animal and a decrease in productivity, and the animal does not require any special care. Calf decontamination is carried out in a slightly different way. There are the following ways to prevent horn formation in calves.

The thermal method is the simplest and safest, used in calves aged 3-6 weeks. Hair is cut short around the horny tubercles (rudiments), and then the horny tubercles are cauterized for 10-15 seconds with a red-hot iron or a special electric device (such as an electric soldering iron), Paquelin or Dechery apparatus.

The chemical method is used in calves 1-2 weeks of age. Hair is cut around the horny tubercles, the skin is wiped with alcohol, light scratches are applied to the horny tubercles with a metal brush. After that, a mixture consisting of 28% antimony trichloride, 7% salicylic acid and 65% collodion is applied to the horny tubercles, or caustic potassium, or caustic soda, or nitric acid is rubbed into them. However, rubbing alkalis and acids is more dangerous, as it can damage the eyes of calves, your hands, and the udders of cows. Rubbing alkalis in calves up to 2 weeks of age is carried out in the area of ​​​​the horn germ with a diameter of up to 1 cm, and in 3-4-week-old calves - with a diameter of up to 1.5 cm. The surgical method is based on the fact that calves up to 8 weeks of age have horns mainly associated with the skin. They can be easily removed with a metal tube (the diameter of which should be 1-2 mm larger than the diameter of the horn process) with an edge pointed at one end. This operation is best performed on 15-20 day old calves. The operation technique is as follows. Hair is cut around the horn process, the skin is wiped with iodized alcohol, and the nerves of the horn are anesthetized. In calves under the age of one month, the tube is placed on the area of ​​the germinal tubercles of the horny processes, and by quickly turning it, the tubercles are cut out to the bones of the skull along with the skin surrounding them. In calves at the age of 2 months, the tube is put on the horn and the adjacent skin is cut to the skull bone, then the tube is tilted and the base of the horn is cut. The wound is smeared with tincture of iodine. In case of bleeding, the wound is tamponed. In these cases, bleeding usually stops after 4-5 minutes. The wound heals within 2-3 days without complications.

Conclusion

The purpose of this course work was to study the structure and properties of the skin of farm animals and birds.

In the course of the work done, the structure of the skin of agricultural animals, birds and fur-bearing animals was studied; chemical and physical properties of the skin, derivatives of the skin: crumbs, glands, horny formations of the skin and hair.

An important role in the work of a veterinarian is played by the care of the skin of farm animals. If the skin is contaminated, the functions of thermoregulation and the release of metabolic products through the skin may be impaired. In addition, dirt and decomposition products of sebum and sweat on the surface of the skin contribute to the development of bacteria, including pathogens. Therefore, the skin and the coat covering it must be systematically cleaned.

Knowledge of the anatomical and topographic features of the skin by a veterinary specialist is necessary, since the skin of an animal performs significant physiological and physico-chemical functions. It is one of the most important mechanisms for protecting an animal from external mechanical and chemical damage, exposure to temperature, desiccation, and the penetration of pathogenic microorganisms.

The skin cover forms special devices on the paws of the limbs: elastic crumbs for stepping and touching, at the ends of the fingers there are hard skin tips that reach a significant variety in shape - claws, nails, hooves. On the head of some animals there are horns for protection, skin folds in the form of a horn for better capture of sound waves (outer ear), etc.

The cover of mammals, in addition to hair visible to the naked eye, also contains in its thickness recesses lined with cells, i.e., glands. Glandular formations also turn out to be diverse in structure, and therefore in meaning: some secrete sweat, others - sebum, and others - a special odorous liquid. Even such a food product as milk is produced by skin glands.

Milk is the secret of the mammary glands, subcutaneous fat and fat are valuable food products. As a product of animal origin, leather is a valuable raw material for semi-finished leather and fur products, and wool cover for the manufacture of woolen products and fabrics.

The nature of the structure of the skin and its derivatives is an essential criterion in the practice of animal husbandry, and mainly in animal breeding and breeding.

It is difficult to overestimate the role of the skin in veterinary medicine. Dermatology is one of the progressive branches of veterinary science. The skin is the mirror of the body. Prevention and treatment of skin diseases of agricultural animals, in particular anthropozoonoses, is the most important task of a veterinary specialist.

List of sources used

1 Antipova, L.V. Anatomy and histology of farm animals / L.V. Antipova, V.S. Slobodyanin, S. M. Suleymanov. - M.: KolosS, 2005. - 323 p.

Alexandrovskaya, O.V. Cytology, histology and embryology / O.V. Alexandrovskaya, T.K. Radostina, N.A. Kozlov. - M.: Agropromizdat, 1987. - 413 p.

Vrakin, V.F. Workshop on anatomy and histology with the basics of cytology and embryology of farm animals / V.F. Vrakin, M.V. Sidorova, V.P. Panov, A.E. Semak. - M.: Lan, 2013.- 384 p.

Gudin, V.A. Physiology and ethology of agricultural birds / V.A. Gudin, V.F. Lysov, V.I. Maksimov. - M.: Lan, 2010.- 336 p.

Klimov, A.F. Anatomy of domestic animals / A.F. Klimov, A.I. Akayevsky. - St. Petersburg-Moscow-Krasnodar: Lan, 2011. - 579-590 p.

Kozlov, N.A. General histology / N.A. Kozlov.- St. Petersburg-Moscow-Krasnodar: Lan, 2004.- 223 p.

Khrustaleva, I.V. Anatomy of domestic animals / I.V. Khrustalev. - M.: Kolos, 1994. - 504-505 p.

8 Veterinary medicine - Veterinary medicine for all .- Electron. text, graph. Dan.

Hunting - The main properties of the skins of fur-bearing animals. .- Electron. magazine

"Decorative ferret" - The structure of the skin of fur-bearing animals