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The Prepuce

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Chapter Two: The Prepuce

One must understand the nature and function of the structure that is amputated by circumcision in order to properly evaluate the effects of male circumcision. This chapter provides that information.
General Description
The prepuce traditionally has been described as a simple fold of skin,1 for which the purpose and function are unknown. This is inaccurate. In reality, the prepuce is a complex structure with multiple anatomical and physiological functions.2
The prepuce is a portion of the entire covering of the penis. It is specialized tissue, composed of skin, mucosa, nerves, blood vessels, and muscle fibers.2 It is anchored by the abdominal wall at the proximal end of the penis and at the proximal end of the glans penis. It is not attached to the shaft of the penis, so, after puberty, it is free to slide back and forth, everting and inverting as it does.3 The sliding/rolling back and forth is called the gliding action.3,4
A frenulum is found on the ventral side of the penis. The frenulum serves to tether a movable structure to a non-movable structure. The penile frenulum returns the foreskin to its normal protective forward position.2 Most men report that the frenulum is highly erogenous tissue.
Peripenic Muscle
In the skin of the penis, there is a sheath of dartos fascia muscle fibers — the peripenic muscle.2,3,5 The muscle fibers keep the prepuce snug against the glans penis.3 The fibers of the peripenic muscle sheath form a whorl at the tip of the prepuce, which act as a sphincter,3 especially in infants and children. The sphincter also serves to prevent inadvertent retraction of the prepuce. The peripenic muscle gives the prepuce great elasticity, allows it to stretch, and helps to return the prepuce to its forward, protective position after retraction.2 The elasticity of the prepuce plays an important role in the erogenous and sexual functions of the prepuce.
Immunology
The prepuce covers and protects the glans penis and urinary meatus. In most males, the prepuce protects the sterile urinary tract environment in infancy and maintains the moistness — beneficial to good health — of the mucosal surface of the glans penis throughout life.6 Fleiss et al. (1998) have identified immunological functions that help to protect the body from pathogens:7
  • sphincter action of the preputial orifice functions like a one-way valve, allowing urine to flow out but preventing the entry of infectious contaminants;
  • apocrine glands of the inner prepuce, which secrete lysozyme, an enzyme that breaks down cell walls of pathogens (and also acts against HIV8);
  • sub-preputial moisture that lubricates and protects the mucosa of the glans penis; and
  • high vascularity to bring phagocytes to fight infection.
The epidermis of the prepuce contains Langerhans cells that secrete cytokines,2 hormone-like low-molecular-weight proteins, which regulate the intensity and duration of immune responses.9 de Witte and colleagues (2007) report that the Langerhans cells produce langerin, a substance that provides a barrier to HIV infection.10
Innervation
The prepuce of the newborn male has extensive innervation. Winkelmann (1956) reported, “[t]he principal form of innervation of human newborn prepuce consists of a deep and superficial network of nerve fibres in the dermis.”11 Moldwin & Valderrama (1989) reported an extensive neuronal network in the prepuce.12
The prepuce of adult males is even more extensively innervated. Winkelmann (1959) described the prepuce as a specific erogenous zone with nerves arranged near the surface in rete ridges.13 Taylor et al. (1996) also found nerves near the surface in rete ridges and further described a concentration of nerve endings in a ring of ridged tissue just inside the tip of the prepuce near the mucocutaneous boundary, which he named the ridged band.14 The nerve endings in the ridged band are Meissner's corpuscles and Krause's end-bulbs.
The nerves of the penis, including the preputial nerves, supply sensory input to both the somatosensory and autonomic nervous systems by different routes.2 The sensory input to the somatosensory nervous system is supplied through the dorsal nerve of the penis, and the autonomic nervous system is supplied through the parasympathetic nerves, which run adjacent to and through the wall of the membranous urethra.
The prepuce is provided with an extensive vascular network to bring oxygen to support the heavy innervation.2,7,14
Several writers have commented on the sensitivity of the prepuce. Winkelmann (1956) wrote, “…it is a region of great sensitivity and possessed of an abundant nerve supply,”11 and later (1959) identified the prepuce as a specific erogenous zone.13 Falliers (1970) noted the “sensory pleasure associated with tactile stimulation of the foreskin.”15 A landmark study by Sorrells et al. (2007) of the fine-touch sensitivity of the penis finds that the areas most sensitive to fine touch are on the foreskin.16 Circumcision, therefore, amputates the most sensitive areas of the penis.
Sexual Function
The prepuce is primary, erogenous tissue necessary for normal sexual function.2 In adult life, the gliding action facilitates introitus4 and reduces friction and chafing during coitus.5 The movement and stretching of the prepuce during coitus stimulate the nerve endings in the prepuce, produce erogenous sensation, and eventually ejaculation.18,19 The presence of the prepuce tends to protect the corona of the glans penis from direct stimulation, helps to prevent premature ejaculation20,21 and contributes to female satisfaction.22 (See Chapter Six for a discussion of the sexual harm of prepuce excision.)
Natural Development
The great majority of newborn infant boys are born with the inner surface of the prepuce fused with the glans.2 In addition, the tip of the prepuce at birth usually is too narrow to allow retraction. The duration of these conditions vary with the individual but can last until the completion of puberty or longer. For these two reasons, the non-retractile foreskin is normal in childhood and adolescence and cannot be considered a disease requiring treatment.
The first data on development of the retractile prepuce was provided in 1949 by British pediatrician Douglas Gairdner.22 Gairdner said 80 percent of boys have a retractable foreskin by the age of two years, and 90 percent of boys have a retractable prepuce by the age three. His erroneous information23 has been incorporated into medical textbooks and medical school curricula for decades, and it still is repeated in medical literature today.24
Gairdner’s data are inaccurate23-25 and, unfortunately, most healthcare providers have been taught this inaccurate information,24,25 which contributes to improper diagnosis of “pathological phimosis” in the healthy, normal, non-retractile foreskin. Retractability usually occurs much later than previously believed.2,24,25 About 44 percent of boys have a fully retractable prepuce by age 10-112,27,28,29 and about 95 percent have a fully retractable prepuce by age 18.2,27 Non-retractile foreskin is the more common condition until 10-11 years of age. Thorvaldsen & Meyhoff (2005) report that the mean age of first foreskin retraction is 10.4 years.29 Non-retractile foreskin in childhood and adolescence is not a disease and does not require treatment.
Ballooning of the prepuce in childhood during urination is harmless and self-limiting. Babu et al. (2004) have shown that ballooning does not cause obstructed voiding.30 Ballooning disappears with increasing maturity. No treatment is required.31
References
  1. Williams PL, Warwick R, Dyson M et al. (eds): Gray's Anatomy, 37th ed, Churchill Livingstone, New York, 1989: 1432
  2. Cold CJ, Taylor JR. The prepuce. BJU Int 1999;83 Suppl. 1:34–44. [Full Text]
  3. Lakshmanan S., Prakash S. Human prepuce: some aspects of structure and function. Indian J Surg 1980;44:134–7. [Full Text]
  4. Warren J, Bigelow J. The case against circumcision. Br J Sex Med 1994;21:6–8. [Full Text]
  5. Jefferson G. The peripenic muscle; some observations on the anatomy of phimosis. Surg Gynecol Obstet (Chicago) 1916;23(2):177–81. [Full Text]
  6. Parkash S, Raghuram R, Venkatesan, et al. Sub-preputial wetness - Its nature. Ann Nat Med Sci (India) 1982;18(3):109–12. [Full Text]
  7. Fleiss P, Hodges F, Van Howe RS. Immunological functions of the human prepuce. Sex Trans Inf 1998;74(5):364–7. [Full Text]
  8. Lee-Huang S, Huang PL, Sun Y, et al. Lysozyme and RNases as anti-HIV components in beta-core preparations of human chorionic gonadotropin. Proc Natl Acad Sci U S A 1999;96(6):2678–81. [Full Text]
  9. Stedman’s Medical Dictionary, 26th edition, q.v. "cytokine."
  10. de Witte L, Nabatov A, Pion M, et al. Langerin is a natural barrier to HIV-1 transmission by Langerhans cells. Nat Med 2007;13:367–371. [Abstract]
  11. Winkelmann RK. The cutaneous innervation of human newborn prepuce. J Invest Dermatol 1956 26(1):53–67. [Full Text]
  12. Moldwin RM, Valderrama E. Immunochemical analysis of nerve distribution patterns within prepucial tissue. J Urol 1989;141(4) Part 2:499A. [Abstract]
  13. Winkelmann RK. The erogenous zones: their nerve supply and significance. Mayo Clin Proc 1959;34(2):39–47. [Full Text]
  14. Taylor JR, Lockwood AP, Taylor AJ. The prepuce: specialized mucosa of the penis and its loss to circumcision. Br J Urol 1996;77:291–5. [Full Text]
  15. Falliers CJ. Circumcision (letter). JAMA 1970;214(12):2194. [Full Text]
  16. Sorrells ML, Snyder JL, Reiss MD, et al. Fine-touch pressure thresholds in the adult penis. BJU Int 2007;99:864–9. [Full Text]
  17. Taves D. The intromission function of the foreskin. Med Hypotheses 2002;59(2):180.
  18. Taylor JR. Letter. Can Fam Physician 2003;49:1592. [Full Text]
  19. Taylor JR. Fine touch pressure thresholds in the adult penis (letter). BJU Int 2007;100(1):218. [Full Text]
  20. Zwang G. Functional and erotic consequences of sexual mutilations. In: Denniston GC and Milos MF, eds. Sexual Mutilations: A Human Tragedy New York and London: Plenum Press, 1997.
  21. O'Hara K, O'Hara J. The effect of male circumcision on the sexual enjoyment of the female partner. BJU Int 1999;83 Suppl 1:79–84.
  22. Gairdner D. The fate of the foreskin: a study of circumcision. Br Med J 1949;2:1433–7. [Full Text]
  23. Wright JE. Further to the "Further Fate of the Foreskin." Med J Aust 1994; 160: 134–5. [Full Text]
  24. Hill G. Circumcision for phimosis and other medical indications in Western Australian boys. Med J Aust 2003;178(11):587. [Full Text]
  25. Hill G. Triple incision plasty to treat phimosis: an alternative to circumcision BJU Int 2004;93:636. [Full Text]
  26. Øster J. Further fate of the foreskin: incidence of preputial adhesions, phimosis, and smegma among Danish schoolboys. Arch Dis Child 1968;43:200–3. [Full Text]
  27. 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. [Full Text]
  28. Morales Concepción JC, Cordies Jackson E, Guerra Rodriguez M, et al. ¿Debe realizarse circuncisión en la infancia? Arch Esp Urol 2002;55(7):807–11. [Abstract]
  29. Thorvaldsen MA, Meyhoff H. Patologisk eller fysiologisk fimose? Ugeskr Læger 2005;167(17):1858–62. [Abstract]
  30. Babu R, Harrison SK, Hutton KA. Ballooning of the foreskin and physiological phimosis: is there any objective evidence of obstructed voiding? BJU Int 2004;94(3):384–7. [Full Text]
  31. Simpson ET, Barraclough P. The management of the paediatric foreskin. Aust Fam Physician 1998;27(5):381–3. [Full Text]
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