KERATINIZATION

From Big Medical Encyclopedia

KERATINIZATION (synonym keratinization) — process of education in an organism of horn substance. The Lake is the cornerstone formation in a cell of a complex of eleidin with tonofibrils with formation of keratinaceous fibrilla that is promoted by activity of mitochondrions, ribosomes and nuclear substances of cells.

Diffraction pattern of a part of a cell of a granular layer of epidermis: numerous bunches of tonofibrils (1), kerato-hyaline granules (2) and a part of a kernel of a cell are visible (3); X 10 000.

The horn substance which is formed as a result of O. consists of a keratin (see. Keratins ), eleidin and fat to - t. Eleidin appears in cells of a granular layer of epidermis in the form of so-called kerato-hyaline granules (fig.) and differs on the properties from a keratin and a hyalin. In its structure, in addition to amino acids, apparently, enter fat to - you. In cells of a granular layer of epidermis there are small roundish granules which are also surrounded with a single-layer membrane — so-called keratosoma, keratopodobny contents to-rykh comes to intercellular space and O. of plasma membranes promotes.

Distinguish physiological and pathological keratinization. Fiziol. The lake (orthokeratinization) occurs in epidermis and performs protective function. It consists in education on the surface of epidermis of the corneous layer consisting of many ranks of flat nuclear-free cells — horn scales. Density and thickness of a corneous layer in different sites of skin are various. The corneous layer reaches the greatest thickness in the field of soles (0,5 mm and more); it is the most dense on nails and in bark of a hair. The lake of cells of epidermis proceeds gradually, begins with basal epidermotsit and comes to an end with formation completely of the keratosic cells of a corneous layer. Fiziol. The lake of epidermis is followed by continuous rejection of the keratosic superficial scales.

Patol. The lake is observed where the corneous layer normal is not formed, napr, in a mucous membrane of language, a gullet and a vagina at leukoplakias (see), in an epithelium of a cornea at avitaminosis And, nek-ry tumors, etc. Patol. The lake can be excessively expressed — hyperkeratosis (see), and also incomplete — parakeratosis (see).

See also Dyskeratosis , Skin , Keratoza .


H. T. Raykhlin.

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