Talk:Genital - Male Development

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2010

Penile embryology and anatomy

ScientificWorldJournal. 2010 Jun 29;10:1174-9.

Yiee JH, Baskin LS.

Department of Urology, University of California San Francisco, USA. yieejh@urology.ucsf.edu Abstract

Knowledge of penile embryology and anatomy is essential to any pediatric urologist in order to fully understand and treat congenital anomalies. Sex differentiation of the external genitalia occurs between the 7th and 17th weeks of gestation. The Y chromosome initiates male differentiation through the SRY gene, which triggers testicular development. Under the influence of androgens produced by the testes, external genitalia then develop into the penis and scrotum. Dorsal nerves supply penile skin sensation and lie within Buck's fascia. These nerves are notably absent at the 12 o'clock position. Perineal nerves supply skin sensation to the ventral shaft skin and frenulum. Cavernosal nerves lie within the corpora cavernosa and are responsible for sexual function. Paired cavernosal, dorsal, and bulbourethral arteries have extensive anastomotic connections. During erection, the cavernosal artery causes engorgement of the cavernosa, while the deep dorsal artery leads to glans enlargement. The majority of venous drainage occurs through a single, deep dorsal vein into which multiple emissary veins from the corpora and circumflex veins from the spongiosum drain. The corpora cavernosa and spongiosum are all made of spongy erectile tissue. Buck's fascia circumferentially envelops all three structures, splitting into two leaves ventrally at the spongiosum. The male urethra is composed of six parts: bladder neck, prostatic, membranous, bulbous, penile, and fossa navicularis. The urethra receives its blood supply from both proximal and distal directions.

PMID: 20602076 http://www.ncbi.nlm.nih.gov/pubmed/20602076

http://www.thescientificworld.co.uk/TSW/toc/TSWJ_ArticleLanding.asp?ArticleId=3497


Neuroanatomical ontogeny of the human fetal penis

Br J Urol. 1997 Apr;79(4):628-40.

Baskin LS, Lee YT, Cunha GR.

Department of Urology, University of California School of Medicine San Francisco, USA. Abstract OBJECTIVE: To determine the development of the human penis, and hence the cause of congenital anomalies, using an immunohistochemical analysis of fetal penile ontogeny.

MATERIALS AND METHODS: In 25 human fetal penile specimens (gestational age 8 to 23 weeks) various tissues were localized immunohistochemically using stains for alpha-actin (smooth muscle), cytokeratin 8 and 14 (epithelium) and protein gene-product (PGP) 9.5 (neurons).

RESULTS: Nerves were identified in the penis with anti-PGP in specimens of all ages, prominent dorsally at the 11 and 1 o'clock positions but also extending around the tunica to the junction of the corpus spongiosum and corpora cavernosa, suggesting that these structures may be injured in procedures which straighten the penis. The nerves continued into the glans on the dorsal aspect, suggesting that glans reduction in feminizing genitoplasties should be performed on the ventral aspect. Smooth muscle was first noted at 10 weeks' gestation, with epithelial differentiation occurring in the earliest specimens studied (8 weeks' gestation). With time, smooth muscle density was highest in the corpus spongiosum, especially between it and the corpora cavernosa. Smooth muscle also developed close to the urethral epithelium. The tunica albuginea showed consistent variations in thickness, with the mid-dorsal 12 o'clock position being the thickest, followed by the 5 and 7 o'clock periurethral positions.

CONCLUSION: A better knowledge of penile development and of the relationship of the nerves to the corpora cavernosa is useful in the strategic design of penile straightening procedures and feminizing genitoplasties.

PMID: 9126098