Editing Smegma

{{Short description|Secretion of mammalian genitals}}
{{about|a secretion of mammalian genitals|the substance that covers the skin of a baby at birth|Vernix caseosa|the experimental noise band|Smegma (band)}}

'''Smegma''' (from [[Ancient Greek]] {{langx|grc|σμῆγμα|smêgma|soap|label=none}})<ref>{{cite Merriam-Webster|smegma|access-date=2017-03-02}}</ref> is [[Exfoliation (cosmetology)|shed]] [[Epithelium|skin cells]], skin oils, and moisture that occurs in 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==
[[File:Female Smegma.jpg|thumb|left|Human [[vulva]] with visible smegma between the labia|200x200px]]
The accumulation of [[sebum]] combined with dead skin cells forms smegma. ''Smegma clitoridis'' is defined as the secretion of the [[apocrine]] (sweat) and sebaceous (sebum) glands of the clitoris in combination with [[Desquamation|desquamating]] epithelial cells.<ref>
{{cite web
 |title=Medical Dictionary
 |url=http://www.medilexicon.com/medicaldictionary.php?t=82565
 |publisher=Medilexicon
}}</ref> 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).<ref>{{cite journal |last1=Aerts |first1=Leen |last2=Rubin |first2=Rachel S. |last3=Randazzo |first3=Michael |last4=Goldstein |first4=Sue W. |last5=Goldstein |first5=Irwin |title=Retrospective Study of the Prevalence and Risk Factors of Clitoral Adhesions: Women's Health Providers Should Routinely Examine the Glans Clitoris |journal=Sexual Medicine |date=June 2018 |volume=6 |issue=2 |pages=115–122 |doi=10.1016/j.esxm.2018.01.003 |pmid=29559206 |pmc=5960030 }}</ref><ref>{{cite journal |last1=Rubin |first1=Rachel |last2=Minton |first2=Julea |last3=Gagnon |first3=Catherine |last4=Winter |first4=Ashley |last5=Goldstein |first5=Irwin |title=PD25-02 Taking Responsibility for Female Prepucial Disorders: Urologic Management of Phimosis-Based Clitorodynia |journal=Journal of Urology |date=April 2017 |volume=197 |issue=4S |doi=10.1016/j.juro.2017.02.1197 |s2cid=78573467 }}</ref><ref>{{cite journal |last1=Parada |first1=Mayte |last2=D'Amours |first2=Tanya |last3=Amsel |first3=Rhonda |last4=Pink |first4=Leah |last5=Gordon |first5=Allan |last6=Binik |first6=Yitzchak M. |title=Clitorodynia: A Descriptive Study of Clitoral Pain |journal=The Journal of Sexual Medicine |date=August 2015 |volume=12 |issue=8 |pages=1772–1780 |doi=10.1111/jsm.12934 |pmid=26104318 }}</ref><ref>{{cite journal |last1=Shafik |first1=A. |title=The Role of the Levator Ani Muscle in Evacuation, Sexual Performance and Pelvic Floor Disorders |journal=International Urogynecology Journal |date=November 2000 |volume=11 |issue=6 |pages=361–376 |doi=10.1007/pl00004028 |pmid=11147745 |s2cid=29636705 }}</ref>

==Males==
[[File:Smegma Penis02.mirrored.jpg|thumb|[[Human penis]] with visible smegma behind the glans|165x165px]]

In males, smegma helps keep the [[Glans penis|glans]] moist and facilitates [[sexual intercourse]] by acting as a lubricant.<ref name="Wright1970">
{{cite journal
 |last=Wright |first=J.
 |date=September 1970
 |title=How smegma serves the penis: Nature's assurance that the uncircumcised glans penis will function smoothly is provided by smegma
 |url=http://www.cirp.org/library/normal/wright1/
 |journal=Sexology
 |volume=37 |issue=2 |pages=50–53
 |name-list-style=vanc
}}</ref><ref name="VanHowesmegma">
{{cite journal
 |last1=Van Howe |first1=R. S.
 |last2=Hodges |first2=F. M.
 |date=October 2006
 |title=The carcinogenicity of smegma: debunking a myth
 |url=http://www.cirp.org/library/disease/cancer/vanhowe2006
 |journal=Journal of the European Academy of Dermatology and Venereology
 |volume=20 |issue=9 |pages=1046–1054
 |doi=10.1111/j.1468-3083.2006.01653.x
 |pmid=16987256
 |s2cid=22840346
 |name-list-style=vanc
}}</ref><ref name="Fleiss">
{{cite journal
 |last1=Fleiss |first1=P. M.
 |last2=Hodges |first2=F. M.
 |last3=Van Howe |first3=R. S.
 |date=October 1998
 |title=Immunological functions of the human prepuce
 |journal=Sexually Transmitted Infections
 |volume=74 |issue=5 |pages=364–367
 |doi=10.1136/sti.74.5.364
 |pmc=1758142
 |pmid=10195034
 |name-list-style=vanc
}}</ref>

Smegma was originally thought to be produced by [[sebaceous gland]]s near the [[Penile frenulum|frenulum]] called [[Preputial gland|Tyson's glands]]; however, subsequent studies have failed to find these glands.<ref name="Parkashsmegma">
{{cite journal
 |last1=Parkash |first1=Satya
 |last2=Jeyakumar |first2=S.
 |last3=Subramanyan |first3=K.
 |last4=Chaudhuri |first4=S.
 |date=August 1973
 |title=Human subpreputial collection: its nature and formation
 |url=http://www.cirp.org/library/anatomy/parkash/
 |journal=Journal of Urology
 |volume=110 |issue=2 |pages=211–212
 |doi=10.1016/s0022-5347(17)60164-2
 |pmid=4722614
 |name-list-style=vanc
}}</ref> 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.<ref name="Wright1970"/> Parkash ''et al.'' found that smegma contains 26.6% fats and 13.3% proteins, which they judged to be consistent with necrotic epithelial debris.<ref name="Parkashsmegma"/> 

Newly produced smegma has a smooth, moist texture. It is thought to be rich in [[squalene]]<ref>
{{cite journal
 |last1=O'Neill |first1=H. J.
 |last2=Gershbein |first2=L. L.
 |year=1976
 |title=Lipids of human and equine smegma
 |journal=Oncology
 |volume=33 |issue=4 |pages=161–166
 |doi=10.1159/000225134
 |pmid=1018879
 |name-list-style=vanc
}}</ref> and contain prostatic and seminal secretions, desquamated [[epithelial cells]], and the mucin content of the [[Urethral gland|urethral glands of Littré]].<ref name="Fleiss"/> Smegma contains [[cathepsin B]], [[lysozymes]],<ref>
{{cite journal
 |last1=Frohlich |first1=E.
 |last2=Schaumburg-Lever |first2=G.
 |last3=Klessen |first3=C.
 |date=1993
 |title=Immunelectron microscopic localization of cathepsin B in human exocrine glands
 |journal=Journal of Cutaneous Pathology
 |volume=20 |issue=1 |pages=54–60
 |doi=10.1111/j.1600-0560.1993.tb01250.x
 |pmid=8468418
 |s2cid=1326013
 |name-list-style=vanc
}}</ref> chymotrypsin, neutrophil elastase<!-- This is possibly not stated in the reference - chymotrypsin and neutrophil elastase is not stated as found in smegma in the abstract --> and [[cytokines]], which aid the immune system.<ref>
{{cite journal
 |last1=Chukwuemeka Anyanwu |first1=Lofty-John
 |last2=Kashibu |first2=Emmanuel
 |last3=Edwin |first3=Chinagozi Precious
 |last4=Mohammad |first4=Aminu Mohammad
 |year=2012
 |title=Microbiology of smegma in boys in Kano, Nigeria
 |journal=Journal of Surgical Research
 |volume=173 |issue=1 |pages=21–25
 |doi=10.1016/j.jss.2011.04.057
 |pmid=21872267
 |name-list-style=vanc
}}</ref>

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.<ref name="Wright1970"/> 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).<ref name=":0">
{{cite journal |last1=Oster |first1=J. |name-list-style=vanc |date=April 1968 |title=Further fate of the foreskin. Incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys |journal=Archives of Disease in Childhood |volume=43 |issue=228 |pages=200–3 |doi=10.1136/adc.43.228.200 |pmc=2019851 |pmid=5689532 |quote="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."}}</ref>

== 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.<ref name=":0" /> 

Smegma can cause irritation and inflammation in men, which can increase the risk of [[penile cancer]]. In the past some experts used to be concerned smegma itself might cause cancer.<ref name=ACS>{{cite web |publisher=[[American Cancer Society]] |title=Risk Factors for Penile Cancer |date=25 June 2018 |url=https://www.cancer.org/cancer/types/penile-cancer/causes-risks-prevention/risk-factors.html}}</ref>

==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]]''.<ref>
{{cite journal
 |last1=Chen |first1=X. G.
 |last2=Li |first2=J.
 |year=2001
 |title=Increasing the sensitivity of PCR detection in bovine preputial smegma spiked with ''Tritrichomonas foetus'' by the addition of agar and resin
 |journal=Parasitology Research
 |volume=87 |issue=7 |pages=556–558
 |doi=10.1007/s004360100401
 |pmid=11484853
 |s2cid=7671511
 |name-list-style=vanc
}}</ref> Accumulation of smegma in the [[equine]] [[foreskin|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]].<ref>Primary Industries Ministerial Council of Australia and New Zealand (2002). [http://www.animalhealthaustralia.com.au/fms/Animal%20Health%20Australia/AUSVETPLAN/cemfinal.pdf Disease strategy: Contagious equine metritis] {{Webarchive|url=https://web.archive.org/web/20080721001616/http://www.animalhealthaustralia.com.au/fms/Animal%20Health%20Australia/AUSVETPLAN/cemfinal.pdf |date=2008-07-21 }} (Version 1.0). In: Australian Veterinary Emergency Plan (AUSVETPLAN), Edition 3, PIMCANZ, Canberra, ACT.</ref> Some equine veterinarians have recommended [[horse sheath cleaning|periodic cleaning of male genitals]] to improve the health of the animal.<ref>{{cite web |first1=Michael |last1=Lowder |date=1 September 2001 |url=http://www.horsecity.com/stories/090101/hea_beans_ML.shtml |title=A Clean Sheath Is A Healthy Sheath |archive-url=https://web.archive.org/web/20050914114048/http://www.horsecity.com/stories/090101/hea_beans_ML.shtml |archive-date=14 September 2005 |work=Horse City }}</ref>

==See also==
* [[Keratin pearl]]
* [[List of cutaneous conditions]]
* ''[[Mycobacterium smegmatis]]'' – found in smegma

== References ==
{{Reflist|30em}}

==External links==
{{Commons category|Smegma}}
* {{cite journal |last1=Neubert |first1=U |last2=Lentze |first2=I |title=Die bakterielle Flora des Präputialraumes |trans-title=The bacterial flora of preputial space |language=de |journal=Hautarzt |date=March 1979 |volume=30 |issue=3 |pages=149–153 |pmid=35486 }}
* {{cite journal |last1=Marzuillo |first1=Pierluigi |last2=Guarino |first2=Stefano |last3=Furlan |first3=Daniela |last4=Pecoraro |first4=Anna |last5=Pedullà |first5=Marcella |last6=Miraglia del Giudice |first6=Emanuele |last7=La Manna |first7=Angela |title=Cleaning the genitalia with plain water improves accuracy of urine dipstick in childhood |journal=European Journal of Pediatrics |date=October 2018 |volume=177 |issue=10 |pages=1573–1579 |doi=10.1007/s00431-018-3215-x |pmid=30054720 |s2cid=51726930 }}
* {{cite book |doi=10.1007/978-3-030-37621-5_17 |chapter=Smegma |title=Normal and Abnormal Prepuce |year=2020 |last1=Fahmy |first1=Mohamed A. Baky |pages=153–161 |isbn=978-3-030-37620-8 |s2cid=243171662 }}

[[Category:Excretion]]
[[Category:Exocrine system]]
[[Category:Mammal female reproductive system]]
[[Category:Mammal male reproductive system]]