Cat

Knowledge about the physiological structure of cat skin, what little secrets are hidden in the cat’s body? There are many different types of cat skin diseases, and they will also show different symptoms. So what is the ultimate explanation of skin diseases? It is a disease whose symptoms are manifested on the skin. When making a diagnosis of skin disease, we should first have a preliminary understanding of the cat’s skin structure, understand the layers of the skin, what are the different physiological structures, and the various parts of the skin. What is its function? This is not only helpful for the judgment of skin diseases, but also helpful for the treatment of medication.

1. Epidermis

The epidermis forms the outermost layer of the skin, which serves to isolate the harsh external environment and protect the body from various chemicals. , physical and biological factors. Although the epidermis is very thin, it has a strong protective effect on the body with the help of hair, keratinocytes and glands. The epidermis and dermis are closely combined, exchanging cells and body fluids to obtain adequate nutrient supply. The epidermis is composed of stratified squamous (flat) epithelium, and its thickness is only 0.2-0.5mm. The thickest epidermis is found on the nose and foot pads (1.5mm). The epidermis is composed of keratinocytes, pigment cells, Langerhans cells, etc. Keratinocytes account for 85% of epidermal cells, and the shapes of each layer in the epidermis are slightly different. The basal layer shows a tightly connected columnar epithelium, which is connected to the basement membrane area. As the cells divide, the daughter cells enter the spinous layer, which is polyhedral in shape, and the granular layer is flat. The stratum corneum appears as a flat shape with missing cell nuclei. Keratinocytes are both an important structural component of the skin and an important member of the skin's immune system. Their ability to phagocytose and process antigens is even higher than that of Langerhans cells, the specialized immune cells in the epidermis. Under the influence of gamma interferon, keratinocytes have a stimulating and buffering effect on T lymphocytes. After interacting with antigens, they produce interleukin-1, which further stimulates the production of a wider range of cytokines, stimulating and suppressing immune responses. Interleukin-1 can also be released into the dermis to cause an inflammatory response.

2. The junction of dermis and epidermis - basement membrane

The basement membrane is the basis of the epidermis. The epidermis is firmly fixed on the dermis through it, maintaining the normal appearance of the epidermis. Function and proliferation, maintain tissue structure, help wound healing, and also serve as a barrier between the dermis and epidermis, maintaining the exchange of cells and body fluid elements between the epidermis and dermis.

The basement membrane is composed of four parts:

(1) Tennofilament-hemidesmosome complex (attached to the basal layer cells);

(2 ) The main components of the transparent plate are collagen Proteins and basement membrane proteoglycans, etc.;

(4) Under the basement membrane: fixed fibers and acid-resistant silks formed by dense thin layers extend to the superficial dermis. Very rare bullous pemphigoid, the main target of autoantibody attack is collagen XVII (BP180).

3. The dermis

is the main part of the skin, with a strong, pliable and elastic texture. The dermis provides physical, blood, and neurological support to the epidermis and is the complete connective tissue of the body. The dermis is mainly composed of dermal fibers and soluble aggregates, with cells dispersed in it. Most of the accessory structures in the skin are located within the dermis.

(1) Dermal fibers: collagen and elastin.

(2) Soluble polymers: proteoglycans and hyaluronan.

(3) Cells in the dermis: fibroblasts and dendritic cells.

(4) Accessory structures: follicular units, arrector pili muscles, blood vessels, lymphatic vessels and nerves. Intradermal lesions frequently occur intravascularly and perivascularly. Other dermal component lesions are very rare, such as: skin lesions caused by abnormalities in collagen structure - Ehlers-Denbach disease (also known as: systemic elastic fiber dysplasia syndrome), which is an inherited disorder of collagen synthesis and distribution. Abnormality, mainly manifested as excessive stretching of the skin.