The sebaceous glands are glands found in the skin of mammals.
Welcome to CWAnswers
CWAnswers is your guide to the sprawling world wide web. The directory aims to provide a useful guide made by users. You can share your knowledge as well - simply sign up and edit your first entry. For questions just contact the team at support - at - cwanswers.com.
Weblinks for Sebum
Top 10 for Sebum
Things about Sebum you find nowhere else.
Select content modules
The sebaceous glands are glands found in the skin of mammals.
Locations and morphology
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.
Sebaceous glands can usually be found in hair-covered areas, where they are connected to hair follicles. The glands deposit sebum on the hairs, and bring it to the skin surface along the hair shaft. The structure consisting of hair, hair follicle, arrector pili muscle, and sebaceous gland is known as a pilosebaceous unit.
Sebaceous glands are also found in non-haired areas (glabrous skin) of eyelids, penis, labia minora, and nipples. Here, the sebum traverses ducts which terminate in sweat pores on the surface of the skin. Pores range in size from 50 to 80 μm on average 1.
The inner surface of the lip and the buccal surface of the cheek can potentially contain ectopic sebaceous glands commonly known as Fordyce's spots or Fordyce granules. These occur as yellowish circular dots that form clusters. Eighty percent of the population have Fordyce granules and these sebaceous glands are asymptomatic.
At the rim of the eyelids, meibomian glands are a specialized form of sebaceous gland. They secrete sebum into the tears coating the eye, to slow evaporation.
Sebum
Sebaceous glands secrete a waxy substance called sebum (Latin, meaning fat or tallow) that is made of fat (lipids) and the debris of dead fat-producing cells. 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 itself is odorless, but its bacterial breakdown can produce odors. Sebum is one cause of some people experiencing "oily" hair or skin if not washed for some time. Earwax is partly composed of sebum.
Sebum acts to protect and waterproof hair and skin, and keep them from becoming dry, brittle, and cracked.Fact: date=September 2008
Composition
The composition of sebum varies from species to species; in humans, the lipid content is as follows:
Changes during development
The sebaceous glands of a human fetus in utero secrete a substance called Vernix caseosa, a "waxy" or "cheesy" white substance coating the skin of newborns.
The activity of the sebaceous glands increases during puberty because of heightened levels of androgens. In males, sebaceous glands begin to appear predominantly on the penis during and after puberty. This is normal, however, and not to be confused with an STD. In females, they appear predominantly in the labia minora.
