Smegma

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

Human vulva with visible female smegma between the labia

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 male 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, itself, is completely benign,[10] but uncircumcised "men with smegma or phimosis have an increased risk of penile cancer."[11]

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.[12] 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.[12]

Newly produced smegma has a smooth, moist texture. It is thought to be rich in squalene[13] 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,[14] chymotrypsin, neutrophil elastase and cytokines, which aid the immune system.[15]

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.[7] Jakob Øster reported that the incidence of smegma increased from 1% among 6- to 7-year-olds and 8- to 9-year-olds to 8% among 14- to 15-year-olds and 16- to 17-year-olds (an overall incidence of 5%).[16]

There is no evidence that smegma, itself, causes penile cancer,[8] but it may harbor cancerous pathogens, like HPV, and its presence over a long period of time may irritate and inflame the penis,[7] which may increase the risk of cancer. It may also make it harder to see very early cancers.[17]

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.[18] 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.[19] Some equine veterinarians have recommended periodic cleaning of male genitals to improve the health of the animal.[20]

See also

Notes

  1. ↑ "smegma". The Merriam-Webster.com Dictionary. Merriam-Webster, Inc. Retrieved 2017-03-02.
  2. ↑ "Medical Dictionary". Medilexicon.
  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. PMC 5960030. 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. S2CID 78573467.
  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. S2CID 29636705.
  7. 1 2 3 4 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.
  8. 1 2 Van Howe RS, Hodges FM (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. S2CID 22840346.
  9. 1 2 Fleiss PM, Hodges FM, Van Howe RS (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.
  10. ↑ McGregor TB, Pike JG, Leonard MP (2007). "Pathologic and physiologic phimosis: Approach to the phimotic foreskin". Canadian Family Physician. 53 (3): 445–8. PMC 1949079. PMID 17872680.
  11. ↑ "Risk Factors for Penile Cancer", American Cancer Society, 2021.
  12. 1 2 Parkash S, 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.
  13. ↑ O'Neill HJ, Gershbein LL (1976). "Lipids of human and equine smegma". Oncology. 33 (4): 161–166. doi:10.1159/000225134. PMID 1018879.
  14. ↑ 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. S2CID 1326013.
  15. ↑ Chukwuemeka Anyanwu L, Kashibu E, Edwin CP, Mohammad AM (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.
  16. ↑ 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. PMC 2019851. PMID 5689532.
  17. ↑ "What are the risk factors for penile cancer?". American Cancer Society. Retrieved 14 February 2014.
  18. ↑ Chen XG, 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. S2CID 7671511.
  19. ↑ Primary Industries Ministerial Council of Australia and New Zealand (2002). Disease strategy: Contagious equine metritis Archived 2008-07-21 at the Wayback Machine (Version 1.0). In: Australian Veterinary Emergency Plan (AUSVETPLAN), Edition 3, PIMCANZ, Canberra, ACT.
  20. ↑ Lowder, Michael (1 September 2001). "A Clean Sheath Is A Healthy Sheath". Horse City. Archived from the original on 14 September 2005.
  • Media related to Smegma at Wikimedia Commons
  • Neubert, U; Lentze, I (March 1979). "Die bakterielle Flora des Präputialraumes" [The bacterial flora of preputial space]. Hautarzt (in German). 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. S2CID 51726930.
  • 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. S2CID 243171662.
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