Smegma

This article is about smegma, usually found in the foreskin, a secretion of mammalian genitals. See Vernix caseosa for the substance that covers the skin of a baby at birth. See Smegma (band) for the experimental noise band.

Smegma (Greek smēgma, "soap"^[1]) is a combination of exfoliated (shed) epithelial cells, transudated skin oils, and moisture. It occurs in both female and male mammalian genitalia.

Human smegma

Both females and males produce smegma. In females, it collects around the clitoris and in the folds of the labia minora; in males, smegma is produced and can collect under the foreskin.

Females

The accumulation of sebum combined with dead skin cells forms smegma. Smegma clitoridis is defined as the secretion of the apocrine glands of the clitoris, in combination with desquamating epithelial cells.^[2] Glands that are located around the clitoris and the vulva majoris secrete sebum. Contaminated, and retained smegma (smegmaliths) usually disappear when the cause is removed.^[3]

Males

Smegma can accumulate on a penis.

In males, smegma helps keep the glans moist and facilitates sexual intercourse by acting as a lubricant.^[4][5][6]

Smegma was originally thought to be produced by sebaceous glands near the frenulum called Tyson's glands; however, subsequent studies have failed to find these glands.^[7] Wright states that smegma is produced from minute microscopic protrusions of the mucosal surface of the foreskin and that living cells constantly grow towards the surface, undergo fatty degeneration, separate off, and form smegma.^[4] Parkash et al. found that smegma contains 26.6% fats and 13.3% proteins, which they judged to be consistent with necrotic epithelial debris.^[7] Newly produced smegma has a smooth, moist texture. It is thought to be rich in squalene^[8] and contain prostatic and seminal secretions, desquamated epithelial cells, and the mucin content of the urethral glands of Littré.^[6] Some state that it contains anti-bacterial enzymes such as lysozyme and hormones such as androsterone,^[5][6] though others dispute this.^[9]

According to Wright, little smegma is produced during childhood, although the foreskin may contain sebaceous glands. She also says that production of smegma increases from adolescence until sexual maturity when the function of smegma for lubrication assumes its full value, and from middle-age production starts to decline and in old age virtually no smegma is produced.^[4] Oster reported that the incidence of smegma increased from 1% among 6-7 year olds to 8% among 16-17 year olds (an overall incidence of 5%).^[10]

In other mammals

In healthy animals, smegma helps clean and lubricate the genitals. In veterinary medicine, analysis of this smegma is sometimes used for detection of urogenital tract pathogens, such as Tritrichomonas foetus.^[11] Accumulation of smegma in the equine preputial folds and the urethral fossa and urethral diverticulum can form large "beans" and promote the carriage of Taylorella equigenitalis, the causative agent of contagious equine metritis.^[12] Some equine veterinarians have recommended periodic cleaning of male genitals to improve the health of the animal.^[13]

Notes

1. ^ "Websters dictionary definition for smegma". Mirriam-Webster. http://www.merriam-webster.com/dictionary/smegma. Retrieved 2008-08-26. 
2. ^ "Medical Dictionary". Medilexicon. http://www.medilexicon.com/medicaldictionary.php?t=82565. 
3. ^ C.F. McDonald, M.D. [1] "Circumcision of the Female"
4. ^ ^{a b c} Wright, Joyce (September 1970). "How smegma serves the penis: Nature's assurance that the uncircumcised glans penis will function smoothly is provided by smegma.". Sexology (New York) 37 (2): 50–53. http://www.cirp.org/library/normal/wright1/. 
5. ^ ^{a b} Van Howe, RS; FM Hodges (October 2006). "The carcinogenicity of smegma: debunking a myth". Journal of the European academy of dermatology and venereology 20 (9): 1046–1054. doi:10.1111/j.1468-3083.2006.01653.x. PMID 16987256. http://www.cirp.org/library/disease/cancer/vanhowe2006. 
6. ^ ^{a b c} Fleiss, P.M.; F.M. Hodges, R.S. Van Howe (October 1998). "Immunological functions of the human prepuce". Sexually transmitted infections 74 (5): 364–367. doi:10.1136/sti.74.5.364. PMC 1758142. PMID 10195034. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1758142. 
7. ^ ^{a b} Parkash, Satya; K. Jeyakumar, K. Subramanya, S. Chaudhuri (August 1973). "Human subpreputial collection: its nature and formation". Journal of urology 110 (2): 211–212. PMID 4722614. http://www.cirp.org/library/anatomy/parkash/. 
8. ^ O'Neill, H.J.; L.L. Gershbein (1976). "Lipids of human and equine smegma". Oncology 33 (4): 161–166. doi:10.1159/000225134. PMID 1018879. 
9. ^ Waskett JH, Morris BJ (January 2008). "Re: 'RS Van Howe, FM Hodges. The carcinogenicity of smegma: debunking a myth.' An example of myth and mythchief making?" (pdf). J Eur Acad Dermatol Venereol 22 (1): 131; author reply 131–2. doi:10.1111/j.1468-3083.2007.02439.x (inactive 2010-03-19). PMID 18182000. http://www3.interscience.wiley.com/cgi-bin/fulltext/119407987/PDFSTART. 
10. ^ Oster J (April 1968). "Further fate of the foreskin. Incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys". Arch. Dis. Child. 43 (228): 200–3. doi:10.1136/adc.43.228.200. PMC 2019851. PMID 5689532. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2019851. 
11. ^ Chen, X.G.; J. Li (2001). "Increasing the sensitivity of PCR detection in bovine preputial smegma spiked with Tritrichomonas foetus by the addition of agar and resin". Parasitol Res 87 (7): 556–558. doi:10.1007/s004360100401. PMID 11484853. 
12. ^ Primary Industries Ministerial Council of Australia and New Zealand (2002). Disease strategy: Contagious equine metritis (Version 1.0). In: Australian Veterinary Emergency Plan (AUSVETPLAN), Edition 3, PIMCANZ, Canberra, ACT.
13. ^ Michael Lowder (September 1, 2001). "A Clean Sheath Is A Healthy Sheath". Horse City. Retrieved on September 4, 2008.