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Undid revision 797087359 by Sugarcube73 (talk) Contradicted by better sources at the Circumcision article.
Delete unhelpful information about "debate" at the WHO. This is not a weak and unsuitable reference.
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The foreskin of adults is typically [[wiktionary:retractable|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.<ref name="Wright"/> The age at which a boy can retract his foreskin varies, but research found that 95% of males were able to fully retract their foreskin by adulthood.<ref>{{vcite journal| author = Øster J | title=Further fate of the foreskin: Incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys |journal=Arch Dis Child |volume=43 |pages=200–202 | date=April 1968 |first=Jakob |last=Øster |publisher=Department of Paediatrics, Central Hospital, Randers, Denmark | doi = 10.1136/adc.43.228.200|pmid=5689532 |pmc=2019851|issue=228}}</ref> Inability to retract the foreskin in childhood should not be considered a problem unless there are other symptoms.<ref>{{cite web |url=http://www.nhs.uk/conditions/phimosis/Pages/Introduction.aspx |title= Phimosis (tight foreskin) |website=NHS Choices |publisher= |accessdate=3 November 2013}}</ref>
The foreskin of adults is typically [[wiktionary:retractable|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.<ref name="Wright"/> The age at which a boy can retract his foreskin varies, but research found that 95% of males were able to fully retract their foreskin by adulthood.<ref>{{vcite journal| author = Øster J | title=Further fate of the foreskin: Incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys |journal=Arch Dis Child |volume=43 |pages=200–202 | date=April 1968 |first=Jakob |last=Øster |publisher=Department of Paediatrics, Central Hospital, Randers, Denmark | doi = 10.1136/adc.43.228.200|pmid=5689532 |pmc=2019851|issue=228}}</ref> Inability to retract the foreskin in childhood should not be considered a problem unless there are other symptoms.<ref>{{cite web |url=http://www.nhs.uk/conditions/phimosis/Pages/Introduction.aspx |title= Phimosis (tight foreskin) |website=NHS Choices |publisher= |accessdate=3 November 2013}}</ref>

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".<ref name=WHO_2007_GTDPSA>{{cite web |title=Male circumcision: Global trends and determinants of prevalence, safety and acceptability |year=2007 |publisher=World Health Organization |url=http://whqlibdoc.who.int/publications/2007/9789241596169_eng.pdf |format=PDF}}</ref>


The foreskin may become subject to a number of pathological conditions.<ref name="Shah2008">{{cite book|author=Manu Shah|title=The Male Genitalia: A Clinician's Guide to Skin Problems and Sexually Transmitted Infections|url=https://books.google.com/books?id=cwede8Un55YC&pg=PA37|date=January 2008|publisher=Radcliffe Publishing|isbn=978-1-84619-040-7|pages=37–}}</ref> Most conditions are rare, and easily treated. In some cases, particularly with [[chronic condition]]s, treatment may include [[circumcision]], a procedure where the foreskin is partially or completely removed.
The foreskin may become subject to a number of pathological conditions.<ref name="Shah2008">{{cite book|author=Manu Shah|title=The Male Genitalia: A Clinician's Guide to Skin Problems and Sexually Transmitted Infections|url=https://books.google.com/books?id=cwede8Un55YC&pg=PA37|date=January 2008|publisher=Radcliffe Publishing|isbn=978-1-84619-040-7|pages=37–}}</ref> Most conditions are rare, and easily treated. In some cases, particularly with [[chronic condition]]s, treatment may include [[circumcision]], a procedure where the foreskin is partially or completely removed.
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Taylor ''et al.'' (1996) described the foreskin in detail, documenting a [[ridged band]] of mucosal tissue. They stated: "This ridged band contains more Meissner's corpuscles than does the smooth mucosa and exhibits features of specialized sensory mucosa."<ref name="taylor" /> In 1999, Cold and Taylor stated: "The prepuce is primary, erogenous tissue necessary for normal sexual function."<ref name="cold-taylor" /> Boyle ''et al.'' (2002) state that "the complex innervation of the foreskin and frenulum has been well documented, and the genitally intact male has thousands of fine touch receptors and other highly erogenous nerve endings."<ref>{{cite journal |title=Male Circumcision: Pain, Trauma and Psychosexual Sequelae |author1=Boyle, G |author2=Goldman, R |author3=Svoboda, J |author4=Fernandez E |journal=Journal of Health Psychology |volume=7 |pages=329–343 |doi=10.1177/135910530200700310 |year=2002 |issue=3 |pmid=22114254}}</ref> The [[American Academy of Pediatrics]] noted that the work of Taylor ''et al.'' (1996) "suggests that there may be a concentration of specialized sensory cells in specific ridged areas of the foreskin."<ref>{{cite journal|title=American Academy of Pediatrics: Circumcision Policy Statement |journal=Pediatrics |date=March 1999 |volume=103 |pages=686–693 |url=http://aappolicy.aappublications.org/cgi/content/full/pediatrics%3b103/3/686 |pmid=10049981 |doi=10.1542/peds.103.3.686 |issue=3 |deadurl=yes |archiveurl=https://web.archive.org/web/20070122014627/http://aappolicy.aappublications.org/cgi/content/full/pediatrics%3B103/3/686 |archivedate=January 22, 2007 |df= }}</ref>
Taylor ''et al.'' (1996) described the foreskin in detail, documenting a [[ridged band]] of mucosal tissue. They stated: "This ridged band contains more Meissner's corpuscles than does the smooth mucosa and exhibits features of specialized sensory mucosa."<ref name="taylor" /> In 1999, Cold and Taylor stated: "The prepuce is primary, erogenous tissue necessary for normal sexual function."<ref name="cold-taylor" /> Boyle ''et al.'' (2002) state that "the complex innervation of the foreskin and frenulum has been well documented, and the genitally intact male has thousands of fine touch receptors and other highly erogenous nerve endings."<ref>{{cite journal |title=Male Circumcision: Pain, Trauma and Psychosexual Sequelae |author1=Boyle, G |author2=Goldman, R |author3=Svoboda, J |author4=Fernandez E |journal=Journal of Health Psychology |volume=7 |pages=329–343 |doi=10.1177/135910530200700310 |year=2002 |issue=3 |pmid=22114254}}</ref> The [[American Academy of Pediatrics]] noted that the work of Taylor ''et al.'' (1996) "suggests that there may be a concentration of specialized sensory cells in specific ridged areas of the foreskin."<ref>{{cite journal|title=American Academy of Pediatrics: Circumcision Policy Statement |journal=Pediatrics |date=March 1999 |volume=103 |pages=686–693 |url=http://aappolicy.aappublications.org/cgi/content/full/pediatrics%3b103/3/686 |pmid=10049981 |doi=10.1542/peds.103.3.686 |issue=3 |deadurl=yes |archiveurl=https://web.archive.org/web/20070122014627/http://aappolicy.aappublications.org/cgi/content/full/pediatrics%3B103/3/686 |archivedate=January 22, 2007 |df= }}</ref>


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."<ref>{{cite web |title=Male circumcision: Global trends and determinants of prevalence, safety and acceptability |publisher=World Health Organization |url=http://whqlibdoc.who.int/publications/2007/9789241596169_eng.pdf |format=PDF|page=16}}</ref> Fink ''et al.'' (2002) reported "although many have speculated about the effect of a foreskin on sexual function, the current state of knowledge is based on anecdote rather than scientific evidence."<ref name="fink">{{cite journal |vauthors=Fink KS, Carson CC, DeVellis RF | title=Adult circumcision outcomes study: effect on erectile function, penile sensitivity, sexual activity and satisfaction | journal=J. Urol. | volume=167 | issue=5 | pages=2113–6 |date=May 2002 | pmid=11956453 | doi= 10.1016/S0022-5347(05)65098-7 | url=http://linkinghub.elsevier.com/retrieve/pii/S0022-5347(05)65098-7}}</ref> Masood ''et al.'' (2005) state that "currently no consensus exists about the role of the foreskin."<ref name="masood">{{cite journal |vauthors=Masood S, Patel HR, Himpson RC, Palmer JH, Mufti GR, Sheriff MK | title=Penile sensitivity and sexual satisfaction after circumcision: are we informing men correctly? | journal=Urol. Int. | year=2005 | volume=75 | issue=1 | pages=62–6 | pmid=16037710 | doi=10.1159/000085930 }}</ref> Schoen (2007) states that "anecdotally, some have claimed that the foreskin is important for normal sexual activity and improves sexual sensitivity.
Fink ''et al.'' (2002) reported "although many have speculated about the effect of a foreskin on sexual function, the current state of knowledge is based on anecdote rather than scientific evidence."<ref name="fink">{{cite journal |vauthors=Fink KS, Carson CC, DeVellis RF | title=Adult circumcision outcomes study: effect on erectile function, penile sensitivity, sexual activity and satisfaction | journal=J. Urol. | volume=167 | issue=5 | pages=2113–6 |date=May 2002 | pmid=11956453 | doi= 10.1016/S0022-5347(05)65098-7 | url=http://linkinghub.elsevier.com/retrieve/pii/S0022-5347(05)65098-7}}</ref> Masood ''et al.'' (2005) state that "currently no consensus exists about the role of the foreskin."<ref name="masood">{{cite journal |vauthors=Masood S, Patel HR, Himpson RC, Palmer JH, Mufti GR, Sheriff MK | title=Penile sensitivity and sexual satisfaction after circumcision: are we informing men correctly? | journal=Urol. Int. | year=2005 | volume=75 | issue=1 | pages=62–6 | pmid=16037710 | doi=10.1159/000085930 }}</ref> Schoen (2007) states that "anecdotally, some have claimed that the foreskin is important for normal sexual activity and improves sexual sensitivity.


The term 'gliding action' is used to describe the way the foreskin moves during sexual intercourse. This mechanism was described by Lakshamanan & Prakash (1980), stating that "[t]he outer layer of the prepuce in common with the skin of the shaft of the penis glides freely in a to and fro fashion..."<ref>{{cite journal |title=Human prepuce: some aspects of structure and function |vauthors=Lakshmanan S, Prakash S |journal=Indian Journal of Surgery |year=1980 |volume=44 |pages=134–137 |quote=The outer layer of the prepuce in common with the skin of the shaft of the penis glides freely in a to and fro fashion and has to be delicate and thin, as was observed in this study. [...] The inner lining of the projecting tubular part has the structure of the outer layer and adds to the thin gliding skin when retracted.}}</ref> Several people have argued that the gliding movement of the foreskin is important during sexual intercourse. Warren & Bigelow (1994) state that gliding action would help to reduce the effects of vaginal dryness and that restoration of the gliding action is an important advantage of [[foreskin restoration]].<ref name="warren-bigelow">{{cite journal |title=The case against circumcision |author1=Warren, J |author2=Bigelow J |journal=Br J Sex Med |date=September–October 1994 |pages=6–8}}</ref> [[Kristen O'Hara|O'Hara]] (2002) describes the gliding action, stating that it reduces friction during [[sexual intercourse]], and suggesting that it adds "immeasurably to the comfort and pleasure of both parties".<ref>{{cite book |title=Sex as Nature Intended It: The Most Important Thing You Need to Know about Making Love, but No One Could Tell You Until Now |author=O'Hara K |page=72 |year=2002 |publisher=Turning Point Publications |quote=During intercourse, the natural penis shaft actually glides within its own shaft skin covering. This minimizes friction to the vaginal walls and opening, and to the shaft skin itself, adding immeasurably to the comfort and pleasure of both parties.<br>Friction is not entirely eliminated during natural intercourse but it is largely eliminated. Friction can take place in the lower vagina, but only if the man uses a stroke that exceeds the (forward and backward) gliding range of the shaft's extra skin. And in such a case, there will be friction only to the extent that the shaft exceeded its extra skin, which is uncommon since the natural penis has a propensity for short strokes. Primarily, it is the penis head that makes frictional contact with the vaginal walls, usually in the upper vagina where there is ample lubrication. [...] The gliding principle of natural intercourse is a two-way street—the vagina glides on the shaft skin while the shaft skin massages the penis shaft as it glides over it.}}</ref> Taylor (2000) suggests that the gliding action, where it occurs, may stimulate the nerves of the [[ridged band]],<ref>{{cite journal |title=Back and Forth |author=Taylor, J |journal=Pediatrics News |volume=34 |year=2000 |page=50 |issue=10}}</ref> and speculates (2003) that the stretching of the frenulum by the rearward gliding action during penetration triggers ejaculation.<ref>{{cite journal |author=Taylor JR |title=Evidence sketchy on circumcision and cervical cancer link |journal=Can Fam Physician |volume=49 |issue= |page=1592 |date=December 2003 |pmid=14708921 |doi= |url=http://www.cfp.ca/cgi/pmidlookup?view=long&pmid=14708921 |pmc=2214164}}</ref> It is argued that removal of the foreskin results in a thickening of the glans because of chafing and abrasion from clothing, leading to loss of sensation. Removal of the foreskin can lead to trauma of the penis (friction irritation) during [[masturbation]] due to the loss of the gliding action of the foreskin and greater friction, requiring artificial lubrication. During sex, the loss of gliding action is also thought to cause pain, dryness and trauma of the [[vagina]].<ref name="warren-bigelow"/> The trauma and abrasions of the vagina can lead to easier entry of sexually transmitted diseases.<ref name="Bullough2014"/> One study showed that the loss of the foreskin resulted in decreased masturbatory pleasure and sexual enjoyment.<ref name='KimPang2007'>{{cite journal | title = The effect of male circumcision on sexuality | journal = BJU Int | date = March 2007 | author = Kim |author2=Pang | volume = 99 | issue = 3 | pages = 619–622| url = | doi=10.1111/j.1464-410X.2006.06646.x | pmid=17155977}}</ref> The gliding action of the foreskin is an aid to [[masturbation]].
The term 'gliding action' is used to describe the way the foreskin moves during sexual intercourse. This mechanism was described by Lakshamanan & Prakash (1980), stating that "[t]he outer layer of the prepuce in common with the skin of the shaft of the penis glides freely in a to and fro fashion..."<ref>{{cite journal |title=Human prepuce: some aspects of structure and function |vauthors=Lakshmanan S, Prakash S |journal=Indian Journal of Surgery |year=1980 |volume=44 |pages=134–137 |quote=The outer layer of the prepuce in common with the skin of the shaft of the penis glides freely in a to and fro fashion and has to be delicate and thin, as was observed in this study. [...] The inner lining of the projecting tubular part has the structure of the outer layer and adds to the thin gliding skin when retracted.}}</ref> Several people have argued that the gliding movement of the foreskin is important during sexual intercourse. Warren & Bigelow (1994) state that gliding action would help to reduce the effects of vaginal dryness and that restoration of the gliding action is an important advantage of [[foreskin restoration]].<ref name="warren-bigelow">{{cite journal |title=The case against circumcision |author1=Warren, J |author2=Bigelow J |journal=Br J Sex Med |date=September–October 1994 |pages=6–8}}</ref> [[Kristen O'Hara|O'Hara]] (2002) describes the gliding action, stating that it reduces friction during [[sexual intercourse]], and suggesting that it adds "immeasurably to the comfort and pleasure of both parties".<ref>{{cite book |title=Sex as Nature Intended It: The Most Important Thing You Need to Know about Making Love, but No One Could Tell You Until Now |author=O'Hara K |page=72 |year=2002 |publisher=Turning Point Publications |quote=During intercourse, the natural penis shaft actually glides within its own shaft skin covering. This minimizes friction to the vaginal walls and opening, and to the shaft skin itself, adding immeasurably to the comfort and pleasure of both parties.<br>Friction is not entirely eliminated during natural intercourse but it is largely eliminated. Friction can take place in the lower vagina, but only if the man uses a stroke that exceeds the (forward and backward) gliding range of the shaft's extra skin. And in such a case, there will be friction only to the extent that the shaft exceeded its extra skin, which is uncommon since the natural penis has a propensity for short strokes. Primarily, it is the penis head that makes frictional contact with the vaginal walls, usually in the upper vagina where there is ample lubrication. [...] The gliding principle of natural intercourse is a two-way street—the vagina glides on the shaft skin while the shaft skin massages the penis shaft as it glides over it.}}</ref> Taylor (2000) suggests that the gliding action, where it occurs, may stimulate the nerves of the [[ridged band]],<ref>{{cite journal |title=Back and Forth |author=Taylor, J |journal=Pediatrics News |volume=34 |year=2000 |page=50 |issue=10}}</ref> and speculates (2003) that the stretching of the frenulum by the rearward gliding action during penetration triggers ejaculation.<ref>{{cite journal |author=Taylor JR |title=Evidence sketchy on circumcision and cervical cancer link |journal=Can Fam Physician |volume=49 |issue= |page=1592 |date=December 2003 |pmid=14708921 |doi= |url=http://www.cfp.ca/cgi/pmidlookup?view=long&pmid=14708921 |pmc=2214164}}</ref> It is argued that removal of the foreskin results in a thickening of the glans because of chafing and abrasion from clothing, leading to loss of sensation. Removal of the foreskin can lead to trauma of the penis (friction irritation) during [[masturbation]] due to the loss of the gliding action of the foreskin and greater friction, requiring artificial lubrication. During sex, the loss of gliding action is also thought to cause pain, dryness and trauma of the [[vagina]].<ref name="warren-bigelow"/> The trauma and abrasions of the vagina can lead to easier entry of sexually transmitted diseases.<ref name="Bullough2014"/> One study showed that the loss of the foreskin resulted in decreased masturbatory pleasure and sexual enjoyment.<ref name='KimPang2007'>{{cite journal | title = The effect of male circumcision on sexuality | journal = BJU Int | date = March 2007 | author = Kim |author2=Pang | volume = 99 | issue = 3 | pages = 619–622| url = | doi=10.1111/j.1464-410X.2006.06646.x | pmid=17155977}}</ref> The gliding action of the foreskin is an aid to [[masturbation]].

Revision as of 23:48, 24 August 2017

This article is about human foreskin. For foreskin in other mammals, see Penile sheath.
Foreskin
Foreskin partially retracted over the glans penis, with a ridged band visible at the end of the foreskin
Details
PrecursorGenital tubercle, urogenital folds
ArteryDorsal artery of the penis
VeinDorsal veins of the penis
NerveDorsal nerve of the penis
Identifiers
LatinPraeputium
MeSHD052816
TA98A09.4.01.011
TA23675
FMA19639
Anatomical terminology

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.

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.[1] The age at which a boy can retract his foreskin varies, but research found that 95% of males were able to fully retract their foreskin by adulthood.[2] Inability to retract the foreskin in childhood should not be considered a problem unless there are other symptoms.[3]

The foreskin may become subject to a number of pathological conditions.[4] 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.

Description

File:Male anatomy.png
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.

Taylor et al. (1996) reported the presence of Krause end-bulbs and a type of nerve ending called Meissner's corpuscles.[5] Their density is reportedly greater in the ridged band (a region of ridged mucosa at the tip of the foreskin) than in the larger area of smooth mucosa.[5] They are affected by age: their incidence decreases after adolescence.[6] Meissner's corpuscles could not be identified in all individuals.[7] Bhat et al studied Meissner's corpuscles at a number of different sites, including the "finger tips, palm, front of forearm, sole, lips, prepuce of penis, dorsum of hand and dorsum of foot". They found the lowest Meissner's Index (density) in the foreskin, and also reported that corpuscles at this site were physically smaller. Differences in shape were also noted. They concluded that these characteristics were found in "less sensitive areas of the body".[8] In the late 1950s, Winkelmann suggested that some receptors had been wrongly identified as Meissner's corpuscles.[9][10]

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."[11]

Development

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.[12]

According to a 1949 study by Gairdner, the foreskin is usually still fused with the glans at birth.[12] As childhood progresses, they gradually separate.[13] There are differing reports on the age at which the foreskin can be retracted. Thorvaldsen and Meyhoff (2005) reported that 21% of 7-year-old boys in their study had non-retractable foreskins and this proportion dropped to 7% at puberty, with first retraction at an average age of 10.4 years[14] but Gairdner (1949) reported that only 10% of 3-year-old boys had non-retractable foreskins,[12] however, Gairdner was wrong about development of foreskin retraction.[1][15] Wright (1994) argues that forcible retraction of the foreskin should be avoided and that the child himself should be the first one to retract his own foreskin.[1] Attempts to forcibly retract it can be painful and may cause injury.[16]

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. Schöberlein (1966) conducted a study of 3,000 young men from Germany and found that 49.6% had the glans fully covered by foreskin, 41.9% were partially covered and 8.5% were uncovered - around half of which (4%) had the foreskin atrophied spontaneously without previous surgery.[17] 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.[18] 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.[19] 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.[20] 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.[21]

Functions

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 state 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".[22] The foreskin helps to provide sufficient skin for full expansion of the shaft during an erection.[23] The Nordic Association of Clinical Sexology states that the foreskin "contributes to the natural functioning of the penis during sexual activity."[24]

Sexual

The foreskin is specialised tissue that is packed with nerves and contains stretch receptors.[5][25][26] Sorrells et al. (2007) reported the areas of the penis most sensitive to fine touch are on the foreskin.[27]

The foreskin enables the penis to slip in and out of the vagina non-abrasively inside its own sheath of self lubricating, movable skin.[28]

Taylor et al. (1996) described the foreskin in detail, documenting a ridged band of mucosal tissue. They stated: "This ridged band contains more Meissner's corpuscles than does the smooth mucosa and exhibits features of specialized sensory mucosa."[5] In 1999, Cold and Taylor stated: "The prepuce is primary, erogenous tissue necessary for normal sexual function."[25] Boyle et al. (2002) state that "the complex innervation of the foreskin and frenulum has been well documented, and the genitally intact male has thousands of fine touch receptors and other highly erogenous nerve endings."[29] The American Academy of Pediatrics noted that the work of Taylor et al. (1996) "suggests that there may be a concentration of specialized sensory cells in specific ridged areas of the foreskin."[30]

Fink et al. (2002) reported "although many have speculated about the effect of a foreskin on sexual function, the current state of knowledge is based on anecdote rather than scientific evidence."[31] Masood et al. (2005) state that "currently no consensus exists about the role of the foreskin."[32] Schoen (2007) states that "anecdotally, some have claimed that the foreskin is important for normal sexual activity and improves sexual sensitivity.

The term 'gliding action' is used to describe the way the foreskin moves during sexual intercourse. This mechanism was described by Lakshamanan & Prakash (1980), stating that "[t]he outer layer of the prepuce in common with the skin of the shaft of the penis glides freely in a to and fro fashion..."[33] Several people have argued that the gliding movement of the foreskin is important during sexual intercourse. Warren & Bigelow (1994) state that gliding action would help to reduce the effects of vaginal dryness and that restoration of the gliding action is an important advantage of foreskin restoration.[34] O'Hara (2002) describes the gliding action, stating that it reduces friction during sexual intercourse, and suggesting that it adds "immeasurably to the comfort and pleasure of both parties".[35] Taylor (2000) suggests that the gliding action, where it occurs, may stimulate the nerves of the ridged band,[36] and speculates (2003) that the stretching of the frenulum by the rearward gliding action during penetration triggers ejaculation.[37] It is argued that removal of the foreskin results in a thickening of the glans because of chafing and abrasion from clothing, leading to loss of sensation. Removal of the foreskin can lead to trauma of the penis (friction irritation) during masturbation due to the loss of the gliding action of the foreskin and greater friction, requiring artificial lubrication. During sex, the loss of gliding action is also thought to cause pain, dryness and trauma of the vagina.[34] The trauma and abrasions of the vagina can lead to easier entry of sexually transmitted diseases.[26] One study showed that the loss of the foreskin resulted in decreased masturbatory pleasure and sexual enjoyment.[38] The gliding action of the foreskin is an aid to masturbation. The Nordic Association of Clinical Sexology states that the foreskin has numerous sexual functions and that "during sexual activity the foreskin is a functional and highly sensitive, erogenous structure, capable of providing pleasure to its owner and his potential partners."[24] 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'."[39]

Protective and immunological

The Nordic Association of Clinical Sexology (2013) states the foreskin has numerous important protective functions including protecting the penile glans from trauma.[24] Gairdner (1949) states that the foreskin protects the glans.[12] The foreskin can protect the glans from ammonia and feces for infants in diapers, and protect the glans from abrasions and trauma throughout life.[23] The fold of the prepuce maintains sub-preputial wetness, which mixes with exfoliated skin to form smegma. The American Academy of Pediatrics (1999) state that "no controlled scientific data are available regarding differing immune function in a penis with or without a foreskin."[40] Inferior hygiene has been associated with balanitis,[41] though excessive washing can cause non-specific dermatitis.[42]

Evolution

In primates, the foreskin is present in the genitalia of both sexes and likely has been present for millions of years of evolution.[43] The evolution of complex penile morphologies like the foreskin may have been influenced by females.[44][45][46]

The foreskin is also suggested to aid in the absorption of vaginal secretions, which contain hormones like vasopressin, that helps induce pair bonding and protective behaviors in the male.[47]

Conditions

Simmons et al. (2007) said, "Genital morphology evolves to provide the primary and secondary functionality that is critical for successful mating." They further reported that the foreskin's presence "frequently predisposes to medical problems, including balanitis, phimosis, sexually transmitted infection and penile cancer", and additionally state that "because we now are able to effectively treat foreskin related maladies, some societies are shifting toward foreskin preservation."[48]

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. Before adulthood, the foreskin may still be separating from the glans.[49] Phimosis can be treated by stretching of the foreskin, by changing masturbation habits,[50] using topical steroid ointments, preputioplasty, or by the more radical option of circumcision. 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.

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.[51]

Aposthia is a rare condition in which the foreskin is not present at birth.

Surgical and non-surgical modifications of the foreskin

Non-surgical stretching of the foreskin

The foreskin responds to the application of tension to cause expansion by creating new skin cells though the process of mitosis. The tissue expansion is permanent. Non-surgical stretching of the foreskin may be used to widen a narrow, non-retractable foreskin.[52] Stretching may be combined with the use of a steroid cream.[53][54] Beaugé recommends manual stretching for young males in preference to circumcision as a treatment for non-retractile foreskin because of the preservation of sexual sensation.[50]

Non-surgical foreskin restoration techniques (developed to help circumcised men 'regrow' a skin covering for the glans by tissue expansion) can be used by men with short foreskins to lengthen the natural foreskin so that it covers the glans.[55]

Surgical modifications

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 a minor procedure designed to relieve a tight foreskin without resorting to circumcision.

Circumcision is the removal of the foreskin, either partially or completely. It may be done for religious requirements or personal preferences surrounding hygiene and aesthetics. A non-surgical circumcision technique was introduced in 2009 with the Prepex device that induces necrosis of the foreskin with no cutting of live tissue.[56] Circumcision alters the penis's appearance, sensitivity, and function.[24]

Other practices include genital piercings involving the foreskin and slitting the foreskin.[57]

Langerhans cells

Langerhans cells are immature dendritic cells that are found in all areas of the penile epithelium,[58] but are most superficial in the inner surface of the foreskin.[58] Langerhans cells are also known to express the c-type lectin langerin.[58]

Foreskin-based medical and consumer products

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.[59]

Human growth factors derived from newborns' foreskins are used to make a commercial anti-wrinkle skin cream, TNS Recovery Complex.[60]

Foreskins of babies are also used for skin graft tissue,[61][62][63] and for β-interferon-based drugs.[64]

Foreskin fibroblasts have been used in biomedical research.[65]

See also

References

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  2. ^ Øster J. Further fate of the foreskin: Incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys. Arch Dis Child. April 1968;43(228):200–202. doi:10.1136/adc.43.228.200. PMID 5689532.
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  9. ^ Winkelmann RK. The cutaneous innervation of human newborn prepuce. J Investigative Dermatol. 1956;26(1):53–67. doi:10.1038/jid.1956.5. PMID 13295637.
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  12. ^ a b c d Gaidner D. Fate of the Foreskin. BMJ. 1949;2(4642):1433–7. doi:10.1136/bmj.2.4642.1433. PMID 15408299.
  13. ^ Øster J. Further fate of the foreskin: incidence of preputial adhesions, phimosis, and smegma among Danish Schoolboys. Arch Dis Child. 1968;43:200–3. doi:10.1136/adc.43.228.200. PMID 5689532.
  14. ^ Thorvaldsen MA, Meyhoff H. Phimosis: Pathological or Physiological?. Ugeskrift for Læger. 2005;167(17):1858–62. PMID 15929334.
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  24. ^ a b c d Nordic Association of Clinical Sexologists. Statement on Non-therapeutic circumcision of boys; 10 October 2013 [Retrieved 6 January 2016].
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  28. ^ Fleiss P, Hodges F, Van Howe RS. Immunological functions of the human prepuce. Sex Transm Infect. 1998;94(5):364-7. doi:10.1136/sti.74.5.364. PMID 10195034. PMC 1758142.
  29. ^ Boyle, G; Goldman, R; Svoboda, J; Fernandez E (2002). "Male Circumcision: Pain, Trauma and Psychosexual Sequelae". Journal of Health Psychology. 7 (3): 329–343. doi:10.1177/135910530200700310. PMID 22114254.
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  31. ^ Fink KS, Carson CC, DeVellis RF (May 2002). "Adult circumcision outcomes study: effect on erectile function, penile sensitivity, sexual activity and satisfaction". J. Urol. 167 (5): 2113–6. doi:10.1016/S0022-5347(05)65098-7. PMID 11956453.
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  33. ^ Lakshmanan S, Prakash S (1980). "Human prepuce: some aspects of structure and function". Indian Journal of Surgery. 44: 134–137. The outer layer of the prepuce in common with the skin of the shaft of the penis glides freely in a to and fro fashion and has to be delicate and thin, as was observed in this study. [...] The inner lining of the projecting tubular part has the structure of the outer layer and adds to the thin gliding skin when retracted.
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  35. ^ O'Hara K (2002). Sex as Nature Intended It: The Most Important Thing You Need to Know about Making Love, but No One Could Tell You Until Now. Turning Point Publications. p. 72. During intercourse, the natural penis shaft actually glides within its own shaft skin covering. This minimizes friction to the vaginal walls and opening, and to the shaft skin itself, adding immeasurably to the comfort and pleasure of both parties.
    Friction is not entirely eliminated during natural intercourse but it is largely eliminated. Friction can take place in the lower vagina, but only if the man uses a stroke that exceeds the (forward and backward) gliding range of the shaft's extra skin. And in such a case, there will be friction only to the extent that the shaft exceeded its extra skin, which is uncommon since the natural penis has a propensity for short strokes. Primarily, it is the penis head that makes frictional contact with the vaginal walls, usually in the upper vagina where there is ample lubrication. [...] The gliding principle of natural intercourse is a two-way street—the vagina glides on the shaft skin while the shaft skin massages the penis shaft as it glides over it.
  36. ^ Taylor, J (2000). "Back and Forth". Pediatrics News. 34 (10): 50.
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  49. ^ Kayaba H, Tamura H, Kitajima S, et al. Analysis of shape and retractability of the prepuce in 603 Japanese boys. J Urol. 1996;156(5):1813–5. doi:10.1016/S0022-5347(01)65544-7. PMID 8863623.
  50. ^ a b Beaugé M. The causes of adolescent phimosis. Br J Sex Med. 1997;(September–October):26.
  51. ^ Chi C, Kirtschig G, Bakio M, et aL.. Topical interventions for genital lichen sclerosus. Cochrane. 2011. doi:10.1002/14651858.CD008240.pub2. PMID 22161424.
  52. ^ Dunn HP. Non-surgical management of phimosis. Aust N Z J Surg. 1989;59(12):963. doi:10.1111/j.1445-2197.1989.tb07640.x. PMID 2597103.
  53. ^ Zampieri N, Corroppolo M, Giacomello L, et al.. Phimosis: Stretching methods with or without application of topical steroids?. J Pediatr. 2005;147(5):705-6. doi:10.1016/j.jpeds.2005.07.017. PMID 16291369.
  54. ^ Ghysel C, Vander Eeckt K, Bogaert GA.. Long-term efficiency of skin stretching and a topical corticoid cream application for unretractable foreskin and phimosis in prepubertal boys. Urol Int. 2009;82(1):81-8. doi:10.1159/000176031. PMID 19172103.
  55. ^ Collier R. Whole again: the practice of foreskin restoration. CMAJ. 2011;183(18):2092-3. doi:10.1503/cmaj.109-4009. PMID 22083672.
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  59. ^ McKie, Robin (1999-04-04). "Foreskins for Skin Grafts". The Toronto Star.
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  61. ^ High-Tech Skinny on Skin Grafts; 1999-02-16 [archived October 10, 2008; Retrieved 2008-08-20].
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  65. ^ Hovatta O, Mikkola M, Gertow A, et al.. A culture system using human foreskin fibroblasts as feeder cells allows production of human embryonic stem cells. Hum Reprod. 2003;18(7):1404–9. doi:10.1093/humrep/deg290. PMID 12832363.
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