- They secrete an oily substance called sebum (Latin, meaning fat or tallow) that is made of fat (lipids) and the debris of dead fat-producing cells. A branched type of Acinar gland, these glands exist in humans throughout the skin except in the palms of the hands and soles of the feet.
- Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle, and cracked. It can also inhibit the growth of microorganisms on skin.
- Sebaceous glands can usually be found in hair-covered areas where they are connected to hair follicles to deposit sebum on the hairs, and bring it to the skin surface along the hair shaft.
- The structure consisting of hair, hair follicle and sebaceous gland is known as pilosebaceous unit.
- Sebaceous glands are also found in non haired areas of lips, eyelids, penis, labia minora and nipples; here the sebum reaches the surface through ducts.
- In the glands, sebum is produced within specialized cells and is released as these cells burst; sebaceous glands are thus classified as holocrine glands
- Sebum is odorless, but its bacterial breakdown can produce odors. Sebum is the cause of some people experiencing "oily" hair if it is not washed for several days. Earwax is partly sebum.
- The composition of sebum varies from species to species; in humans, the lipid content consists of about 25% wax monoesters, 41% triglycerides, 16% free fatty acids, and 12% squalene.
- Sebaceous cyst
- Alternative names - Epidermal cyst; Keratin cyst; Epidermoid cyst
- Sebaceous cysts are sacs just beneath the skin that are filled with an oily, white, semisolid material called sebum
- Duct obstruction of a sebaceous gland in the hair follicle can result in a long, narrow channel opening in the surface comedo
Sebacous Cysts also called as Epidermoid cyst - forms due to obstruction of the duct of the sebaceous gland.
Treatment of Sebacous Cyst is Excision