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Foreskin

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Foreskin
A penis with a relatively short foreskin partially covering the glans.
Details
PrecursorGenital tubercle, Urogenital folds
ArteryDorsal artery of the penis
VeinSuperficial dorsal vein of the penis
NerveDorsal nerve of the penis
Identifiers
Latinprepucium, præputium
MeSHD052816
TA98A09.4.01.011
TA23675
FMA19639
Anatomical terminology

In male human anatomy, the foreskin is a generally retractable double-layered fold of skin and mucous membrane that covers the glans penis and protects the urinary meatus (Template:Pron-en) when the penis is not erect. 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.

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. Like the eyelid, the foreskin is free to move after it separates from the glans, usually by puberty. Smooth muscle fibres keep it close to the glans but make it highly elastic.[1] The foreskin is attached to the glans by a frenulum, which helps return the foreskin over the glans. At the end of the foreskin, there is a band of tissue called the ridged band, which, according to Cold and Taylor, contains nerve endings called Meissner's corpuscles.[2][3] (Some authors have reported the presence of these receptors in the foreskin as a whole.[4][5][6][7][8] However, Winkelmann has noted that the literature on the subject is conflicting, and the descriptions of the receptors found do not agree; he argues that the structures are not Meissner's corpuscles.[9]) According to a study by Sorrells et al. (2007), the five most sensitive areas of the penis are on the foreskin;[10] this is disputed by Waskett and Morris, who argue that re-analysis of Sorrells' data shows no significant differences.[11] In 2009, Schober et al reported on self-assessed sexual sensitivity in 81 men, 11 of whom were intact. When assessing areas producing sexual pleasure, the foreskin was ranked 7th, after the glans, lower and upper shaft, and the left and right sides of the penis, but above the area between scrotum and anus, the scrotum itself, and the anus.[12]

In children, the foreskin usually covers the glans completely but in adults, this need not be so. Schöberlein [13] found that about 50% of young men had full coverage of the glans, 42% had partial coverage, and, in the remaining 8%, the glans was uncovered. After adjusting for circumcision, he stated that, in 4% of the young men, the foreskin had spontaneously atrophied (shrunk). There is considerable variation in the degree to which the foreskin retracts during erection; in some adults the foreskin remains covering the glans until retracted by sexual activity.

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.[14]

At birth, the foreskin is usually still fused with the glans.[14] As childhood progresses the foreskin and the glans gradually separate, a process that may not be complete until late puberty.[15] Thorvaldsen and Meyhoff reported that average age of first foreskin retraction in Denmark is 10.4 years.[16] Wright 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.[17] Attempts to forcibly retract it can be painful and may injure the foreskin.[18]

Functions

The foreskin typically covers the glans when the penis is flaccid (left), but generally retracts upon erection (right)

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".[19]

Sexual

Further information: Sexual effects of circumcision

Taylor et al. 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."[3] In 1999, Cold and Taylor stated: "The prepuce is primary, erogenous tissue necessary for normal sexual function."[2] Boyle et al. 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—many of which are lost to circumcision, with an inevitable reduction in sexual sensation experienced by circumcised males."[20] The AAP noted that the work of Taylor et al. "suggests that there may be a concentration of specialized sensory cells in specific ridged areas of the foreskin."[21]

Moses and Bailey (1998) describe the evidence of sensory function as "indirect," and state that, "aside from anecdotal reports, it has not been demonstrated that this is associated with increased male sexual pleasure."[22] The World Health Organization states that there is little evidence for diminished sexual function, adding that studies have been inconsistent.[23] Fink et al. reported "[a]lthough 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."[24] Masood et al. state that "[c]urrently no consensus exists about the role of the foreskin or the effect circumcision has on penile sensitivity and overall sexual satisfaction."[25] Schoen states that "[a]necdotally, some have claimed that the foreskin is important for normal sexual activity and improves sexual sensitivity. Objective published studies over the past decade have shown no substantial difference in sexual function between circumcised and uncircumcised men."[26]

The term 'gliding action' is used in some papers to describe the way the foreskin moves during sexual intercourse. This mechanism was described by Lakshamanan & Prakash in 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..."[27] Several people have argued that the gliding movement of the foreskin is important during sexual intercourse.[28] Warren & Bigelow claim 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.[29] O'Hara 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".[30] Taylor suggests that the gliding action, where it occurs, may stimulate the nerves of the ridged band,[31] and speculates that the stretching of the frenulum by the rearward gliding action during penetration triggers ejaculation.[32]

Whiddon (1953) and Foley (1966) also believed that the presence of the foreskin made sexual penetration easier.[33][34]

Other

Gairdner (1949) states that the foreskin protects the glans[14] but some studies show that inflammation of the glans is more common when the foreskin is present.[35]

The fold of the prepuce maintains sub-preputial wetness, which mixes with exfoliated skin to form smegma. Some authors believe that smegma contains antibacterial enzymes,[36] though their theory has been challenged.[37] The American Academy of Pediatrics state that "no controlled scientific data are available regarding differing immune function in a penis with or without a foreskin."[38] Inferior hygiene has been associated with balanitis,[39] though excessive washing can cause non-specific dermatitis.[40]

Evolution

In primates, the foreskin is present in the genitalia of both sexes and likely has been present for millions of years of evolution.[41] The evolution of complex penile morphologies like the foreskin may have been influenced by females.[42][43][44] It has been proposed that the foreskin evolved to facilitate masturbation.[45]

Conditions

Frenulum breve is where the frenulum is insufficiently long to allow the foreskin to fully retract, which may lead to discomfort during intercourse. The frenulum may also tear 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.[46]) Phimosis can be treated by gently stretching the foreskin, by changing masturbation habits,[47] using topical steroid ointments, preputioplasty, or by circumcision.

Non-retractable foreskin is not always indicative of a clinical condition. The first time the foreskin retracts (say during masturbation or sex) can be a slightly painful experience, as the glans penis is not used to friction and air contact. However the problem resolves itself after a few days of acclimatization, which may include consciously retracting the foreskin and exposing it to air, water, or friction. 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 ischaemia of the glans penis.

Some South Korean doctors claim that South Korean men have a gene that causes “abundant foreskin,” believing that at least 90% of Korean men have “too much” foreskin.[48]

Although there is no scientific evidence of this alleged genotype and it was found that most Korean physicians could not define phimosis, almost all of South Korean physicians recommend universal circumcision because they believe it eliminates tight foreskins and brings many benefits.[49][50]

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

Surgical and other modifications of the foreskin

Circumcision is the removal of the foreskin, either partially or completely. It may be done for religious requirements, health reasons such as to treat a medical disorder, or personal preferences surrounding hygiene and aesthetics.

Preputioplasty is a procedure to relieve a tight foreskin without resorting to circumcision.

Foreskin restoration techniques (developed to help circumcised men regrow a skin covering for the glans by tissue expansion) can be used by uncircumcised men with short foreskins to lengthen the natural foreskin so that it covers the glans. A narrow foreskin may be widened by tissue expansion.[51]

Other practices include genital piercings involving the foreskin and slitting the foreskin.[52]

Langerhans cells

Langerhans cells are immature dendritic cells that are found in all areas of the penile epithelium,[53] but are most superficial in the inner surface of the foreskin.[53] A study by Szabo and Short (2000) targets Langerhans cells as receptors of HIV, and states that these cells "must be regarded as the most probable sites for viral entry in primary HIV infection in men."[54] Langerhans cells are also known to express the c-type lectin langerin, which may play a role in transmission of HIV to nearby lymph nodes.[53] However, de Witte et al. (2007) reported that langerin, produced by Langerhans cells, blocks the transmission of HIV to T cells.[55]

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.[56]

Foreskins from circumcised babies are used to make a commercial anti-wrinkle skin cream. A six-week supply of one formula, TNS Recovery Complex, costs US$130.[citation needed]

Foreskins of babies are also used for skin graft tissue,[57][58][59] and for β-interferon-based drugs.[60]

Foreskin fibroblasts have been used in biomedical research.[61]

Additional images

  • Caravaggio's Amor Victorious with the Roman Cupid Amor showing his penis with foreskin
    Caravaggio's Amor Victorious with the Roman Cupid Amor showing his penis with foreskin
  • Statue of Gomateshwara which features a penis with a foreskin
    Statue of Gomateshwara which features a penis with a foreskin
  • Michelangelo's David features a penis with a foreskin
    Michelangelo's David features a penis with a foreskin
  • Composite image showing a penis with the foreskin having been retracted (left), and placed back in usual position covering the glans (right)
    Composite image showing a penis with the foreskin having been retracted (left), and placed back in usual position covering the glans (right)

Foreskin in non-human species

In koalas, the foreskin contains naturally-occurring bacteria that play an important role in fertilization.[62] Almost all mammal penises have foreskins, although in non-human cases the foreskin is usually a sheath into which the whole penis is retracted. Only monotremes (the platypus and the echidna) lack foreskins.[63]

See also

References

  1. ^ Lakshmanan, S (1980). "Human prepuce - structure & function". Indian J Surg. 44: 134–7. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  2. ^ a b Cold, CJ. "The prepuce". BJU Int. 83 Supp 1: 34–44. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  3. ^ a b Taylor, JR (1996). "The prepuce: specialized mucosa of the penis and its loss to circumcision". Br J Urol. 77 (2): 291–5. doi:10.1046/j.1464-410X.1996.85023.x. PMID 8800902. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  4. ^ Haiyang, Jiang (2005-04). "Observation of Meissner's corpuscle in abundant prepuce and phimosis". Journal of Modern Urology. Retrieved 2010-05-07. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ Dong, GUO (2007-01). "Observation of Meissner's corpuscle on fused phimosis". Journal of Guangdong Medical College. CNKI:ISSN:1005-4057.0.2007-01-004. Retrieved 2010-05-07. {{cite journal}}: Check date values in: |date= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ Dogiel, A. S. (1893). "Die Nervenendigungen in der Schloemhaut der ausseren Genitalorgane des Menschen". Aroh. F. Mikr. Anat. 41: 585–612. doi:10.1007/BF02954333. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  7. ^ Ohmori, D. (1924). "Uber die Enwickling der Innervation der Genital Apparatus als peripheren Aufnahme-Apparat der genitalen Reflex". Ztscr. F. D. Ges. Anat. U. Entw. 70: 347–410. doi:10.1007/BF02117201. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  8. ^ Bazett, H. C. (1935). "Methods of investigation of sensation in man and the theoretical value of the results obtained". Proc. A. Research Nerv. & Ment. Dis. 15: 83–97. {{cite journal}}: Cite has empty unknown parameter: |coauthors= (help)
  9. ^ Winkelmann, R. K. (1956-1). "The cutaneous innervation of human newborn prepuce". Journal of Investigative Dermatology. 26 (1): 53–67. PMID 13295637. {{cite journal}}: Check date values in: |date= (help); Cite has empty unknown parameter: |coauthors= (help)
  10. ^ Sorrels, Morris (2007). "Fine-touch pressure thresholds in the adult penis" (PDF). Bjuinternational. 99: 864–869. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  11. ^ Waskett, Jake H. (2007). "Fine touch pressure thresholds in the adult penis". BJU International. 99 (6): 1551–1552. doi:10.1111/j.1464-410X.2007.06970_6.x. PMID 17537227. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  12. ^ Schober JM, Meyer-Bahlburg HF, Dolezal C (2009). "Self-ratings of genital anatomy, sexual sensitivity and function in men using the 'Self-Assessment of Genital Anatomy and Sexual Function, Male' questionnaire". BJU Int. 103 (8): 1096–103. doi:10.1111/j.1464-410X.2008.08166.x. PMID 19245445. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  13. ^ Schöberlein circumcision taboos. Phimosis frenulum and foreskin conditions, phimosis and male initiation
  14. ^ a b c Gairdner, D (1949). "The Fate of The Foreskin: a study of circumcision". BMJ. 2 (4642): 1433–7. doi:10.1136/bmj.2.4642.1433. PMC 2051968. PMID 15408299.
  15. ^ Øster, J (1968). "Further fate of the foreskin: incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys". Arch Dis Child. 43 (228): 200–3. doi:10.1136/adc.43.228.200. PMC 2019851. PMID 5689532.
  16. ^ Phimosis: Pathological or Physiological?
  17. ^ Wright JE (1994). "Further to "the further fate of the foreskin". Update on the natural history of the foreskin". Med. J. Aust. 160 (3): 134–5. PMID 8295581. {{cite journal}}: Unknown parameter |month= ignored (help)
  18. ^ "Circumcision of infant males" (PDF). RACP. p. 7.
  19. ^ "Male circumcision: Global trends and determinants of prevalence, safety and acceptability" (PDF). World Health Organization. p. 18.
  20. ^ Boyle, G; Goldman, R; Svoboda, J; Fernandez E (2002). "Male Circumcision: Pain, Trauma and Psychosexual Sequelae". Journal of Health Psychology. 7: 329–343. doi:10.1177/1359105302007003225.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ "American Academy of Pediatrics: Circumcision Policy Statement". Pediatrics. 103 (3): 686–693. 1999. doi:10.1542/peds.103.3.686. PMID 10049981. {{cite journal}}: Unknown parameter |month= ignored (help)
  22. ^ Moses S (1998). "Male circumcision: assessment of health benefits and risks". Sexually Transmitted Infections. 74 (5): 368–373. doi:10.1136/sti.74.5.368. PMC 1758146. PMID 10195035. Retrieved 2007-04-28. There is indirect evidence suggesting that the foreskin may have an important sensory function, although aside from anecdotal reports, it has not been demonstrated that this is associated with increased male sexual pleasure. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  23. ^ "Male circumcision: Global trends and determinants of prevalence, safety and acceptability" (PDF). World Health Organization. p. 22. 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.
  24. ^ Fink KS, Carson CC, DeVellis RF (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. {{cite journal}}: Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  25. ^ Masood S, Patel HR, Himpson RC, Palmer JH, Mufti GR, Sheriff MK (2005). "Penile sensitivity and sexual satisfaction after circumcision: are we informing men correctly?". Urol. Int. 75 (1): 62–6. doi:10.1159/000085930. PMID 16037710.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  26. ^ Schoen EJ (2007). "Should newborns be circumcised? Yes". Can Fam Physician. 53 (12): 2096–8, 2100–2. PMC 2231533. PMID 18077736. {{cite journal}}: Unknown parameter |month= ignored (help)
  27. ^ 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.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  28. ^ Kigozi G, Watya S, Polis CB; et al. (2008). "The effect of male circumcision on sexual satisfaction and function, results from a randomized trial of male circumcision for human immunodeficiency virus prevention, Rakai, Uganda". BJU Int. 101 (1): 65–70. doi:10.1111/j.1464-410X.2007.07369.x. PMID 18086100. Opponents of circumcision, using results from selected observational studies, have argued that the procedure impairs sexual function, and reduces sexual pleasure and satisfaction through keratinization of the glans, removal of the most sensitive preputial tissues, and loss of the 'gliding' mechanism provided by the foreskin {{cite journal}}: Explicit use of et al. in: |author= (help); Unknown parameter |month= ignored (help)CS1 maint: multiple names: authors list (link)
  29. ^ Warren, J; Bigelow J (September/October 1994). "The case against circumcision". Br J Sex Med: 6–8. {{cite journal}}: Check date values in: |date= (help)CS1 maint: multiple names: authors list (link)
  30. ^ 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.
  31. ^ Taylor, J (2000). "Back and Forth". Pediatrics News. 34 (10): 50.
  32. ^ Taylor JR (2003). "Evidence sketchy on circumcision and cervical cancer link". Can Fam Physician. 49: 1592. PMC 2214164. PMID 14708921. {{cite journal}}: Unknown parameter |month= ignored (help)
  33. ^ WHIDDON D (1953). "I. Should baby be circumcised?". Lancet. 265 (6781): 337–8. PMID 13085774. {{cite journal}}: Unknown parameter |month= ignored (help)
  34. ^ The Unkindest Cut of All
  35. ^ Balanitis and the uncircumcised male
  36. ^ Immunological Functions of the Human Prepuce
  37. ^ STI -- eLetters for Fleiss et al., 74 (5) 364-367
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  39. ^ O'Farrell N, Quigley M, Fox P (2005). "Association between the intact foreskin and inferior standards of male genital hygiene behaviour: a cross-sectional study". Int J STD AIDS. 16 (8): 556–9. doi:10.1258/0956462054679151. PMID 16105191.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  40. ^ Birley: Management of Recurrent Balanitis
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  42. ^ Diamond, Jared M. (1997). Why Sex is Fun: The Evolution of Human Sexuality. London: Weidenfeld & Nicolson. ISBN 0465031269.
  43. ^ Darwin, Charles (1871). The Descent of Man and Selection in Relation to Sex. London: Murray. ISBN 1148750932.
  44. ^ 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.
  45. ^ Cox, Guy (1995). "De virginibus puerisque: The function of the human foreskin considered from an evolutionary perspective". Med Hypotheses. 45 (6): 617–21. doi:10.1016/0306-9877(95)90248-1. PMID 8771059. {{cite journal}}: Unknown parameter |unused_data= ignored (help)
  46. ^ Kayaba: Normal Development of the Prepuce
  47. ^ The causes of adolescent phimosis
  48. ^ Jung, K. M. 1971. A study on the foreskin and circumcision of the penis of Korean male. Korean Journal of Public Health 8:369
  49. ^ Kim, D. S., J. Y. Lee, & M. G. Pang. 1999. Male circumcision: A South Korean perspective. British Journal of Urology International, 83, Supplement; 1:28-33.
  50. ^ International Encyclopedia of Sexuality, South Korea, The Kinsey Institute. Edited by Hyung-Ki Choi, M.D., Ph.D., and Huso Yi, Ph.D.
  51. ^ Dunn HP. Non-surgical management of phimosis. Aust N Z J Surg 1989;59(12):963.
  52. ^ eMedicine - Paraphimosis : Article by Jong M Choe, MD, FACS
  53. ^ a b c McCoombe SG, Short RV (2006). "Potential HIV-1 target cells in the human penis". AIDS. 20 (11): 1491–5. doi:10.1097/01.aids.0000237364.11123.98. PMID 16847403.
  54. ^ "How does male circumcision protect against HIV infection?". Retrieved 2007-11-30.
  55. ^ de Witte L, Nabatov A, Pion M; et al. (2007). "Langerin is a natural barrier to HIV-1 transmission by Langerhans cells". Nat. Med. 13 (3): 367–71. doi:10.1038/nm1541. PMID 17334373. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  56. ^ McKie, Robin (1999-04-04). "Foreskins for Skin Grafts". The Toronto Star. {{cite news}}: |access-date= requires |url= (help)
  57. ^ "High-Tech Skinny on Skin Grafts". www.wired.com:science:discoveries. CondéNet, Inc. 02.16.99. Retrieved 2008-08-20. {{cite web}}: Check date values in: |date= (help)
  58. ^ "Skin Grafting". www.emedicine.com. WebMD. Retrieved 2008-08-20.
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  60. ^ 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.
  61. ^ Hovatta, O. (2003). "A culture system using human foreskin fibroblasts as feeder cells allows production of human embryonic stem cells". Human Reproduction. 18 (7): 1404–1409. doi:10.1093/humrep/deg290. PMID 12832363. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  62. ^ UQ researchers unlock another koala secret
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(WMP, streaming) http://www.doctorsopposingcircumcision.org/video/prepuce.html
(WMP, download) http://www.doctorsopposingcircumcision.org/video/Circumcision_WM7NTSC_256k_D.wmv
  • Anatomy photo:42:01-0107 at the SUNY Downstate Medical Center - "The Male Perineum and the Penis: The Surface Anatomy of the Penis"
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