Biology:Smegma

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Short description: Secretion of mammalian genitals


Smegma (Ancient Greek σμῆγμα : smēgma[1]) is a combination of shed skin cells, skin oils, and moisture. It occurs in both male and female mammalian genitalia. In females, it collects around the clitoris and in the folds of the labia minora; in males, smegma collects 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, the labia minora, and the labia majora secrete sebum.

If smegma is not removed frequently it can lead to clitoral adhesion which can make clitoral stimulation (such as masturbation) painful (clitorodynia).[3][4][5][6]

Males

Human penis with visible smegma behind the glans

In males, smegma helps keep the glans moist and facilitates sexual intercourse by acting as a lubricant.[7][8][9]

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.[10] Joyce 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.[7] Parkash et al. found that smegma contains 26.6% fats and 13.3% proteins, which they judged to be consistent with necrotic epithelial debris.[10]

Newly produced smegma has a smooth, moist texture. It is thought to be rich in squalene[11] and contain prostatic and seminal secretions, desquamated epithelial cells, and the mucin content of the urethral glands of Littré.[9] Smegma contains cathepsin B, lysozymes,[12] chymotrypsin, neutrophil elastase and cytokines, which aid the immune system.[13]

According to Wright, the production of smegma, which is low in childhood, increases from adolescence until sexual maturity when the function of smegma for lubrication assumes its full value. From middle-age, production starts to decline and in old age virtually no smegma is produced.[7] Jakob Øster reported that the incidence of smegma increased from 1% among 6- to 9-year-olds to 8% among 14- to 17-year-olds (amongst those who did not present with phimosis and could be examined).[14]

Clinical significance and hygiene

The production of smegma, which increases during puberty, can only be of limited significance, as males and females learn to practice good genital hygiene.[14]

Men with smegma have an elevated risk of developing penile cancer.[15] This is generally thought to be because of irritation caused by smegma, and not by the properties of smegma itself.[15]

Other animals

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.[16] 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.[17] Some equine veterinarians have recommended periodic cleaning of male genitals to improve the health of the animal.[18]

See also

  • Keratin pearl
  • List of cutaneous conditions
  • Mycobacterium smegmatis – found in smegma

References

  1. ↑ "smegma". smegma. Merriam-Webster, Inc.. http://www.merriam-webster.com/dictionary/smegma. Retrieved 2017-03-02. 
  2. ↑ "Medical Dictionary". Medilexicon. http://www.medilexicon.com/medicaldictionary.php?t=82565. 
  3. ↑ Aerts, Leen; Rubin, Rachel S.; Randazzo, Michael; Goldstein, Sue W.; Goldstein, Irwin (June 2018). "Retrospective Study of the Prevalence and Risk Factors of Clitoral Adhesions: Women's Health Providers Should Routinely Examine the Glans Clitoris". Sexual Medicine 6 (2): 115–122. doi:10.1016/j.esxm.2018.01.003. PMID 29559206. 
  4. ↑ Rubin, Rachel; Minton, Julea; Gagnon, Catherine; Winter, Ashley; Goldstein, Irwin (April 2017). "PD25-02 Taking Responsibility for Female Prepucial Disorders: Urologic Management of Phimosis-Based Clitorodynia". Journal of Urology 197 (4S). doi:10.1016/j.juro.2017.02.1197. 
  5. ↑ Parada, Mayte; D'Amours, Tanya; Amsel, Rhonda; Pink, Leah; Gordon, Allan; Binik, Yitzchak M. (August 2015). "Clitorodynia: A Descriptive Study of Clitoral Pain". The Journal of Sexual Medicine 12 (8): 1772–1780. doi:10.1111/jsm.12934. PMID 26104318. 
  6. ↑ Shafik, A. (November 2000). "The Role of the Levator Ani Muscle in Evacuation, Sexual Performance and Pelvic Floor Disorders". International Urogynecology Journal 11 (6): 361–376. doi:10.1007/pl00004028. PMID 11147745. 
  7. ↑ 7.0 7.1 7.2 Wright, J. (September 1970). "How smegma serves the penis: Nature's assurance that the uncircumcised glans penis will function smoothly is provided by smegma". Sexology 37 (2): 50–53. http://www.cirp.org/library/normal/wright1/. 
  8. ↑ Van Howe, R. S.; Hodges, F. M. (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. 
  9. ↑ 9.0 9.1 Fleiss, P. M.; Hodges, F. M.; Van Howe, R. S. (October 1998). "Immunological functions of the human prepuce". Sexually Transmitted Infections 74 (5): 364–367. doi:10.1136/sti.74.5.364. PMID 10195034. 
  10. ↑ 10.0 10.1 Parkash, Satya; Jeyakumar, S.; Subramanyan, K.; Chaudhuri, S. (August 1973). "Human subpreputial collection: its nature and formation". Journal of Urology 110 (2): 211–212. doi:10.1016/s0022-5347(17)60164-2. PMID 4722614. http://www.cirp.org/library/anatomy/parkash/. 
  11. ↑ O'Neill, H. J.; Gershbein, L. L. (1976). "Lipids of human and equine smegma". Oncology 33 (4): 161–166. doi:10.1159/000225134. PMID 1018879. 
  12. ↑ Frohlich, E.; Schaumburg-Lever, G.; Klessen, C. (1993). "Immunelectron microscopic localization of cathepsin B in human exocrine glands". Journal of Cutaneous Pathology 20 (1): 54–60. doi:10.1111/j.1600-0560.1993.tb01250.x. PMID 8468418. 
  13. ↑ Chukwuemeka Anyanwu, Lofty-John; Kashibu, Emmanuel; Edwin, Chinagozi Precious; Mohammad, Aminu Mohammad (2012). "Microbiology of smegma in boys in Kano, Nigeria". Journal of Surgical Research 173 (1): 21–25. doi:10.1016/j.jss.2011.04.057. PMID 21872267. 
  14. ↑ 14.0 14.1 Oster, J. (April 1968). "Further fate of the foreskin. Incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys". Archives of Disease in Childhood 43 (228): 200–3. doi:10.1136/adc.43.228.200. PMID 5689532. ""The production of smegma increases from the age of 12-13, but our actual figures of the incidence of smegma can only be of limited significance, as the boys received regular instruction about preputial hygiene."". 
  15. ↑ 15.0 15.1 "Risk Factors for Penile Cancer". American Cancer Society. 25 June 2018. https://www.cancer.org/cancer/types/penile-cancer/causes-risks-prevention/risk-factors.html. 
  16. ↑ Chen, X. G.; Li, J. (2001). "Increasing the sensitivity of PCR detection in bovine preputial smegma spiked with Tritrichomonas foetus by the addition of agar and resin". Parasitology Research 87 (7): 556–558. doi:10.1007/s004360100401. PMID 11484853. 
  17. ↑ 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.
  18. ↑ Lowder, Michael (1 September 2001). "A Clean Sheath Is A Healthy Sheath". Horse City. http://www.horsecity.com/stories/090101/hea_beans_ML.shtml. 

External links

  • Neubert, U; Lentze, I (March 1979). "Die bakterielle Flora des Präputialraumes" (in de). Hautarzt 30 (3): 149–153. PMID 35486. 
  • Marzuillo, Pierluigi; Guarino, Stefano; Furlan, Daniela; Pecoraro, Anna; Pedullà, Marcella; Miraglia del Giudice, Emanuele; La Manna, Angela (October 2018). "Cleaning the genitalia with plain water improves accuracy of urine dipstick in childhood". European Journal of Pediatrics 177 (10): 1573–1579. doi:10.1007/s00431-018-3215-x. PMID 30054720. 
  • Fahmy, Mohamed A. Baky (2020). "Smegma". Normal and Abnormal Prepuce. pp. 153–161. doi:10.1007/978-3-030-37621-5_17. ISBN 978-3-030-37620-8. 



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