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In male human anatomy, the foreskin is the double-layered fold of smooth muscle tissue, blood vessels, neurons, skin, and mucous membrane part of the penis that covers and protects the glans penis and the urinary meatus. It is also described as the prepuce, a technically broader term that also includes the clitoral hood in women, to which the foreskin is embryonically homologous. The highly innervated mucocutaneous zone of the penis occurs near the tip of the foreskin. The foreskin is mobile, fairly stretchable, and acts as a natural lubricant.

Foreskin
Foreskin of a human penis.jpg
Foreskin partially retracted over the glans penis, with a ridged band visible at the end of the foreskin
Details
Precursor Genital tubercle, urogenital folds
Artery Dorsal artery of the penis
Vein Dorsal veins of the penis
Nerve Dorsal nerve of the penis
Identifiers
Latin Praeputium
MeSH A05.360.444.492.362
Dorlands
/Elsevier
Preupuce
TA A09.4.01.011
FMA 19639
Anatomical terminology

The foreskin of adults is typically retractable over the glans. Coverage of the glans in a flaccid and erect state varies depending on foreskin length. The foreskin is attached to the glans at birth and is generally not retractable in infancy. Inability to retract the foreskin in childhood should not be considered a problem unless there are other symptoms.[1]

The World Health Organization debates the precise functions of the foreskin, which may include "keeping the glans moist, protecting the developing penis in utero, or enhancing sexual pleasure due to the presence of nerve receptors".[2]

The foreskin may become subject to a number of pathological conditions.[3] Most conditions are rare, and easily treated. In some cases, particularly with chronic conditions, treatment may include circumcision, a procedure where the foreskin is partially or completely removed.

Contents

DescriptionEdit

 
Diagram of a portion of the male anatomy

The outside of the foreskin is a continuation of the skin on the shaft of the penis, but the inner foreskin is a mucous membrane like the inside of the eyelid or the mouth. The mucocutaneous zone occurs where the outer and inner foreskin meet. The ridged band of highly innervated tissue is located just inside the tip of the foreskin. Like the eyelid, the foreskin is free to move after it separates from the glans, which usually occurs before or during puberty. The foreskin is attached to the glans by a frenulum, a highly vascularized tissue of the penis.[2] The World Health Organization states that "[t]he frenulum forms the interface between the outer and inner foreskin layers, and when the penis is not erect, it tightens to narrow the foreskin opening.[2]

The human foreskin contains a sheath of muscle tissue just below the skin, formerly known as the peripenic muscle and now called the dartos fascia, most of which is contained in the foreskin. Elastic fibers are contained in the dartos fascia, which form a whorl at the tip of the foreskin. The whorl of fibers acts as a sphincter in infants, which opens to allow the passage of urine, but closes to protect the glans penis from foreign matter and contaminants. The dartos fascia is sensitive to temperature and expands and contracts with temperature changes. The dartos fascia is only loosely connected with the underlying tissue so it provides the skin mobility and elasticity of the penile skin.[medical citation needed]

The College of Physicians and Surgeons of British Columbia has written that the foreskin is "composed of an outer skin and an inner mucosa that is rich in specialized sensory nerve endings and erogenous tissue."[4]

DevelopmentEdit

The foreskin is present in non-human primates, including the chimpanzee.[2]

Eight weeks after fertilization, the foreskin begins to grow over the head of the penis, covering it completely by 16 weeks. At this stage, the foreskin and glans share an epithelium (mucous layer) that fuses the two together. It remains this way until the foreskin separates from the glans.[medical citation needed]

 
Once the foreskin has naturally separated from the glans, the foreskin's two layers of outer skin and inner mucosa can be retracted to reveal the glans, inner foreskin, and ridged band.

In children, the foreskin usually covers the glans completely but in adults it may not. During erection, the degree of automatic foreskin retraction varies considerably; in some adults, the foreskin remains covering all or some of the glans until retracted manually or by sexual activity. This variation was regarded by Chengzu (2011) as an abnormal condition named 'prepuce redundant'. Frequent retraction and washing under the foreskin is suggested for all adults but particularly for those with a long, or 'redundant' foreskin.[5] When the foreskin is longer than the erect penis, it will not spontaneously retract upon erection.

It is shown that manual foreskin retraction during childhood or even adulthood serves as a stimulant to normal development and automatic retraction of the foreskin, which suggests that many conditions affecting the foreskin may be prevented or cured behaviorally.[medical citation needed] Some males, according to Xianze (2012), may be reluctant for their glans to be exposed because of discomfort when it chafes against clothing, although the discomfort on the glans was reported to diminish within one week of continuous exposure.[6] Guochang (2010) states that for those whose foreskins are too tight to retract or have some adhesions, forcible retraction should be avoided since it may cause injury.[7]

FunctionsEdit

 
The foreskin typically covers the glans when the penis is not erect (top image), but generally retracts upon erection (bottom image). Coverage of the glans in a flaccid and erect state varies depending on foreskin length

The World Health Organization (2007) states that there is "debate about the role of the foreskin, with possible functions including keeping the glans moist, protecting the developing penis in utero, or enhancing sexual pleasure due to the presence of nerve receptors".[2] The foreskin helps to provide sufficient skin during an erection.[8]

The foreskin protects the glans.[4] The foreskin protects the glans of infants from ammonia and feces in diapers, which reduces the incidence of meatal stenosis, and continues to protect the glans from abrasions and trauma throughout life.[8] The fold of the prepuce maintains sub-preputial wetness, which mixes with exfoliated skin to form smegma.[citation needed]

The American Academy of Pediatricians' 2012 technical report on circumcision found that the foreskin tends to harbor micro-organisms that can lead to urinary tract infections in infants and tend to contribute to the transmission of sexually transmitted diseases in adults.[9]

SexualEdit

The World Health Organization (2007) states that "Although it has been argued that sexual function may diminish following circumcision due to the removal of the nerve endings in the foreskin and subsequent thickening of the epithelia of the glans, there is little evidence for this and studies are inconsistent."[2]

The foreskin is specialised tissue that is packed with nerves and contains stretch receptors.[10]

The Royal Dutch Medical Association (2010) states that many sexologists view the foreskin as "a complex, erotogenic structure that plays an important role 'in the mechanical function of the penis during sexual acts, such as penetrative intercourse and masturbation'."[11]

EvolutionEdit

In primates, the foreskin is present in the genitalia of both sexes and likely has been present for millions of years of evolution.[12] The evolution of complex penile morphologies like the foreskin may have been influenced by females.[13][14][15]

ConditionsEdit

The foreskin can be involved in balanitis, phimosis, sexually transmitted infection and penile cancer.[16]

Frenulum breve is a frenulum that is insufficiently long to allow the foreskin to fully retract, which may lead to discomfort during intercourse.

Phimosis is a condition where the foreskin of an adult cannot be retracted properly. Phimosis can be treated by using topical steroid ointments and using lubricants during sex; for severe cases circumcision may be necessary.[1] Posthitis is an inflammation of the foreskin.

A condition called paraphimosis may occur if a tight foreskin becomes trapped behind the glans and swells as a restrictive ring. This can cut off the blood supply, resulting in ischemia of the glans penis.[1]

Lichen sclerosus is a chronic, inflammatory skin condition that most commonly occurs in adult women, although it may also be seen in men and children. Topical clobetasol propionate and mometasone furoate were proven effective in treating genital lichen sclerosus.[17]

Some birth defects of the foreskin can occurl all of them are rare. In aposthia there is no foreskin at birth,[18]:37-39 in micropathia the foreskin doesn't cover the glans,[18]:41-45 and in macroposthia, also called and congenital megaprepuce, the foreskin extends well past the end of the glans.[18]:47-50

Surgical and non-surgical modifications of the foreskinEdit

 
Preputioplasty:
Fig 1. Penis with tight phimotic ring making it difficult to retract the foreskin.
Fig 2. Foreskin retracted under anaesthetic with the phimotic ring or stenosis constricting the shaft of the penis and creating a "waist".
Fig 3. Incision closed laterally.
Fig 4. Penis with the loosened foreskin replaced over the glans.

Preputioplasty is the most common foreskin reconstuction technique, most often done when a boy is born with a foreskin that is too small;[19]:177 a similar procedure can be done is done to relieve a tight foreskin without resorting to circumcision.[19]:181

Circumcision is the removal of the foreskin, either partially or completely. For newborns, it may be done for religious requirements or personal preferences surrounding hygiene and aesthetics.[20]:257 Circumcision may also be performed on children or adults to treat phimosis, balanitis, or to prevent transmission of sexually transmitted disease.[21]:166 As of 2012 no successful technique to reconstruct a circumsized foreskin had been published.[19]:181 Some men have used weights to stretch the skin of the penis to regrow a foreskin; the resulting tissue does cover the glans but does not replicate the features of a foreskin.[22]

Other cultural or aesethetic practices include genital piercings involving the foreskin and slitting the foreskin.[23]

Langerhans cellsEdit

Langerhans cells are immature dendritic cells that are found in all areas of the penile epithelium,[24] but are most superficial in the inner surface of the foreskin.[24]

Foreskin-based medical and consumer productsEdit

Foreskins obtained from circumcision procedures are frequently used by biochemical and micro-anatomical researchers to study the structure and proteins of human skin. In particular, foreskins obtained from newborns have been found to be useful in the manufacturing of more human skin.[25]

Foreskins of babies are also used for skin graft tissue,[26][27][28] and for β-interferon-based drugs.[29]

Foreskin fibroblasts have been used in biomedical research.[30]

See alsoEdit

ReferencesEdit

  1. ^ a b c "Phimosis (tight foreskin)". NHS Choices. 26 August 2015. Retrieved 21 September 2017. 
  2. ^ a b c d e f "Male circumcision: Global trends and determinants of prevalence, safety and acceptability" (PDF). World Health Organization. 2007. 
  3. ^ Manu Shah (January 2008). The Male Genitalia: A Clinician's Guide to Skin Problems and Sexually Transmitted Infections. Radcliffe Publishing. pp. 37–. ISBN 978-1-84619-040-7. 
  4. ^ a b College of Physicians; Surgeons of British Columbia (2009). "Circumcision (Infant Male)" (PDF). Archived from the original (PDF) on May 31, 2012. Retrieved April 22, 2012. 
  5. ^ Chengzu, Liu (2011). "Health Care for Foreskin Conditions". Epidemiology of Urogenital Diseases. Beijing: People's Medical Publishing House. 
  6. ^ Xianze, Liang (2012). Tips on Puberty Health. Beijing: People's Education Press. 
  7. ^ Guochang, Huang (2010). General Surgery. Beijing: People's Medical Publishing House. 
  8. ^ a b Dobanavacki D, Lucić Prostran B, Sarac D; et al. (2012). "Prepuce in boys and adolescents: what when, and how?". Med Pregl. 65 (7-8): 295–300. PMID 22924249. 
  9. ^ American Academy of Pediatrics Task Force on, Circumcision. (September 2012). "Male circumcision.". Pediatrics. 130 (3): e756–85. PMID 22926175. doi:10.1542/peds.2012-1990. . The technical report was published in conjunction with an updated statement of policy on circumcision: American Academy of Pediatrics Task Force on Circumcision. (September 2012). "Circumcision policy statement." (PDF). Pediatrics. 130 (3): 585–6. PMID 22926180. doi:10.1542/peds.2012-1989. 
  10. ^ Human Sexuality: An Encyclopedia. Routledge; 14 January 2014. ISBN 978-1-135-82502-7. p. 120–.
  11. ^ "Non-therapeutic circumcision of male minors (2010)". KNMG. 12 June 2010. 
  12. ^ Martin, Robert D. (1990). Primate Origins and Evolution: A Phylogenetic Reconstruction. New Jersey: Princeton University Press. ISBN 978-0-691-08565-4. 
  13. ^ Diamond, Jared M. (1997). Why Sex is Fun: The Evolution of Human Sexuality. London: Weidenfeld & Nicolson. ISBN 0-465-03126-9. 
  14. ^ Darwin, Charles (1871). The Descent of Man and Selection in Relation to Sex. London: Murray. ISBN 1-148-75093-2. 
  15. ^ Short, RV (1981). "Sexual selection in man and the great apes". Graham CE, ed. Reproductive Biology of the Great Apes: Comparative and Biomedical Perspectives. New York: Academic Press. 
  16. ^ Simmons MN, Jones JS (2007). "Male genital morphology and function: an evolutionary perspective". J Urol. 177 (5): 1625–31. PMID 17437774. doi:10.1016/j.juro.2007.01.011. 
  17. ^ Chi C, Kirtschig G, Bakio M, et aL.. Topical interventions for genital lichen sclerosus. Cochrane. 2011. doi:10.1002/14651858.CD008240.pub2. PMID 22161424.
  18. ^ a b c Fahmy, Mohamed (2017). Congenital Anomalies of the Penis - Springer. Springer. ISBN 978-3-319-43310-3. 
  19. ^ a b c Snodgrass, Warren T. (2012). "Chapter 15: Foreskin Reconstruction". In Bolnick, David A.; Koyle, Martin; Yosha, Assaf. Surgical Guide to Circumcision. London: Springer-Verlag. pp. 177–181. ISBN 978-1-4471-2858-8. 
  20. ^ Cox, Guy; Morris, Brian J. (2012). "Chapter 21: Why Circumcision:From Prehistory to the Twenty-First Century". In Bolnick, David A.; Koyle, Martin; Yosha, Assaf. Surgical Guide to Circumcision. London: Springer-Verlag. pp. 243–259. ISBN 978-1-4471-2858-8. 
  21. ^ McClung, Chris; Voelzke, Bryan (2012). "Chapter 14: Adult Circumcision". In Bolnick, David A.; Koyle, Martin; Yosha, Assaf. Surgical Guide to Circumcision. London: Springer-Verlag. pp. 165–175. ISBN 978-1-4471-2858-8. 
  22. ^ Collier R. Whole again: the practice of foreskin restoration. CMAJ. 2011;183(18):2092-3. doi:10.1503/cmaj.109-4009. PMID 22083672.
  23. ^ "Paraphimosis : Article by Jong M Choe, MD, FACS". eMedicine. Retrieved 2012-07-16. 
  24. ^ a b McCoombe SG, Short RV. Potential HIV-1 target cells in the human penis. AIDS. 2006;20(11):1491–5. doi:10.1097/01.aids.0000237364.11123.98. PMID 16847403.
  25. ^ McKie, Robin (1999-04-04). "Foreskins for Skin Grafts". The Toronto Star. 
  26. ^ High-Tech Skinny on Skin Grafts; 1999-02-16 [archived October 10, 2008; Retrieved 2008-08-20].
  27. ^ Grand DJ. Medscape. Skin Grafting; August 15, 2011 [Retrieved August 18. 2012].
  28. ^ Amst, Catherine; Carey, John (July 27, 1998). "Biotech Bodies". www.businessweek.com. The McGraw-Hill Companies Inc. Archived from the original on December 24, 2013. Retrieved 2017-09-17. 
  29. ^ Cowan, Alison Leigh (April 19, 1992). "Wall Street; A Swiss Firm Makes Babies Its Bet". New York Times:Business. New York Times. Retrieved 2008-08-20. 
  30. ^ Hovatta O, Mikkola M, Gertow A; et al. (2003). "A culture system using human foreskin fibroblasts as feeder cells allows production of human embryonic stem cells". Hum Reprod. 18 (7): 1404–9. PMID 12832363. doi:10.1093/humrep/deg290. 

External linksEdit