sebaceous gland

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Any of various glands in the dermis of the skin that open into a hair follicle and produce and secrete sebum.

A gland which produces and liberates sebum, a mixture composed of fat, cellular debris, and keratin. When the gland arises in association with a hair follicle, it forms a thickened outpushing from the side of the developing follicle near the epidermis. Central cells in these sebaceous glands form oil droplets within the cytoplasm. These cells disintegrate to liberate the sebaceous substance and are therefore of the holocrine type. The Meibomian or tarsal glands, within the tarsus or supporting plate at the edge of the eyelids, are sebaceous and complex tubuloacinous structures. The numerous separate glands open along the entire edge of the upper and lower lids. Retained secretions of the tarsal glands produce a chalozion or Meibomian cyst. See also Gland.

Exocrine glands of the skin, many of which open into the hair follicles and secrete an oily substance that coats the hair and surrounding epithelium, helping to prevent evaporation of sweat and retain body heat. In the oral cavity, these glands are known as Fordyce’s granules or Fordyce’s spots and can be seen with the unaided eye as yellowish-white in color and are more common in older adults on the buccal and labial mucosa.

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Glands located in the skin that secrete an oily substance, sebum. Sebum lubricates the skin and hair.

Sebaceous glands are microscopic glands in the skin which secrete an oily matter (sebum) in the hair follicles to lubricate the skin and hair of animals. In humans, they are found in greatest abundance on the face and scalp, though they are distributed throughout all skin sites except the palms and soles.^[1] The extreme use (up to 10 times doctor prescribed amounts) of anabolic steroids by bodybuilders for muscle gain and repartitioning effects tend to stimulate the sebaceous glands which can cause acne.^[2]

Sebum can also build up around body piercings.^[3]

Contents 1 Sebum composition 2 Additional images 3 See also 4 References 5 External links

Sebum composition

The composition of sebum varies from species to species; in humans, the lipid content is as follows:^[4]

Percent composition	Substance
25%	wax monoesters
41%	triglycerides
16%	free fatty acids
12%	squalene

Additional images

Pilosebaceous unit

Base of pilosebaceous unit

Insertion of sebaceous glands into hair shaft

A hair follicle with associated structures.

See also

• Oil gland

References

1. ^ James, William; Berger, Timothy; Elston, Dirk (2005) Andrews' Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. Page 7. ISBN 0721629210.
2. ^ Abuse Of Anabolic Steroids Causes Acne In Bodybuilders, by Medinda.com
3. ^ Playe, Stephen J (July 2002). "Infectious Complications of Body Art: Infection is reported in about 1% of tattoos and in up to 45% of piercings, depending on the technique employed, body location, and after care". Emergency Medicine News 24 (7): 10–13. doi:10.1097/01.EEM.0000334232.52899.06. ISSN 1552-3624. http://www.em-news.com/pt/re/emmednews/abstract.00132981-200207000-00007.htm;jsessionid=J3QHjVQl5vQqyyYhpdNxppJvvBPpkX7jNgj7f6HKFwsk6JhqCtp9!928310026!181195629!8091!-1. 
4. ^ Cheng JB, Russell DW (2004). "Mammalian wax biosynthesis. II. Expression cloning of wax synthase cDNAs encoding a member of the acyltransferase enzyme family". J. Biol. Chem. 279 (36): 37798–807. doi:10.1074/jbc.M406226200. PMID 15220349. http://www4.utsouthwestern.edu/moleculargenetics/pdf/dr_cur_res/JBiolChem2004-II.pdf. 

External links

• MeSH Sebaceous+Glands

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