Sebaceous glands

Sebaceous glands – skin glands, whose secret is fatty lubricant for the surface of skin and hair.

They are located practically on all skin, except for soles of legs and skin of palms. By the sizes they significantly differ, and also have a different structure and localization in different sites of skin. Most of all accumulation of sebaceous glands is observed in a pilar part of the head, and also on a chin and cheeks. They are located and on the sites deprived of hair: in mouth corners, on lips, a clitoris, nipples, small vulvar lips, a balanus, a prepuce.

The arrangement, the sizes and structure of sebaceous glands depends on the term of laying of a hair. They are located in a reticular (mesh) layer of a derma and lie in a little slanting direction between a muscle-podnimatelem of a hair and its folliculomas. At reduction of a muscle of hair becomes straight and puts pressure, promoting secretion of a sebaceous gland.

The simple sebaceous gland consists of an output channel and a trailer secretory part. Vyvodnoy Canal is represented by not keratosic flat epithelium, and a trailer secretory part covered from within – the sack outside surrounded with a thin joint capsule. Under the capsule the rostkovy layer – the undifferentiated cells having high mitotic activity which lie on a basal membrane is located. In the center of a trailer secretory part there is a cellular detritis consisting of the broken-up secretory cells – gland secret.

Blood vessels provide blood supply of glands and feed root system of a hair. Sebaceous glands are supplied with adrenergic and cholinergic nerve fibrils. Adrenergic nerve fibrils probodat a basal membrane and surround secretory cells, and cholinergic nerve fibrils are located on a surface of a basal membrane.

Throughout all human life sebaceous glands change. At the time of birth they are very developed and intensively function. For the first year of life against the background of reduced secretion of sebaceous glands their growth prevails, further they partially atrophy, especially in skin of a back and shins.

During puberty their growth amplifies, increases function of sebaceous glands again.

At advanced age of gland cease to develop that is shown in reduction of their sizes, simplification of a structure, by decrease in functional and metabolic activity of secretory cells. Some glands in general disappear with age.

Normal gland in days allocates about 20 g of skin fat. Secretion of sebaceous glands does a hair elastic, regulates water evaporation, softens epidermis, interferes with penetration into skin of some substances from the outside, renders anti-fungal and antimicrobic effect.

Function of sebaceous glands is regulated in the neurohumoral way by preferential sex hormones which can sometimes cause strengthening of their activity (allocation of too large number of a secret, a hyperplasia). At newborn children hypophyseal maternal hormones and progesterone exert strong impact on glands, and during puberty activation of gonadotropic function of a front part of a hypophysis, strengthening of activity of gonads, activation of bark of adrenal glands acts on them.

Pathologies of sebaceous glands

Pathology of glands consists in malformations, dystrophic changes, functional disturbances, an inflammation of sebaceous glands and tumors of glands.

Dysfunction of sebaceous glands, as a rule, results from defeat vegetative peripheral or the central nervous system, disbolism and hormonal regulation. Often strengthening of activity of glands can be observed at a catatonic stupor, defeats of a front share of a hypophysis, gonads, bark of adrenal glands, and also at epidemic viral encephalitis owing to defeat of the vegetative centers. Leads depression of function of hemadens to depression of function of glands, for example, at an orkhiektomiya.

Often disturbance of work is resulted by obstruction of sebaceous glands. One of the most widespread pathologies which cornerstone disturbance of secretory function is is seborrhea. At this disease in channels of glands there are grease and horn traffic jams, or the comedones resulting from obstruction of sebaceous glands. Also frequent phenomenon is emergence of atheromas – retentsionny cysts. Multiple cysts arise also at a pilosebotsistomatoza owing to disturbance of a nevoid dysplasia of epidermis.

Dystrophic changes can be as age character, and to develop at some acquired diseases (a scleroderma, a skin atrophy, etc.). Often dystrophic changes are caused by hereditary factors.

The inflammation of sebaceous glands arises quite often, especially during puberty. The inflammation is characterized by formation of eels. At the same time inflammatory process can take walls of glands and fabric around them (pustular eels), and can extend also in deeper layers of skin, sometimes even taking hypodermic cellulose (flegmozny eels).

True adenoma of gland most of which often develops at adult and elderly people and looks as a dense round small knot on a back or a face belongs to benign tumors of sebaceous glands.

The bazalioma which has mestnodestruiruyushchy growth belongs to malignant tumors. Most often cancer of a sebaceous gland develops from cartilage glands a century – meibomian glands.