Embryology of Prepuce

Abstract

The embryology of the penis and urogenital region had been controversial and confusing for long time before evolving of recent studies, which emerged extensively during the last decade. The other problem in the previous studies that most of the observations have been extrapolated to the human from many different other species including mice, rats, red squirrels and pigs, and this may leads to misinterpretation of many aspects. At the main time the embryology of the prepuce was not considered earnestly among the genital embryology in the old textbooks. Fetal sex development involves a series of sequential stages, and both differentiation and formation of internal and external genitalia are a late-developmental steps in human ontogeny which are regulated by the action of sex hormones. The human prepuce is formed by a midline collision of ectoderm, neuroectoderm and mesenchyme, resulting in a pentalaminar sheath. The first indication of the onset of the developmental processes of the prepuce involved the appearance of a raised fold (the preputial fold), just at the coronary sulcus. At the same time the floor of the resulting glandopreputial furrow gives rise to a lamellar ingrowth which has been termed “glandar lamella”, these lamella grow gradually to cover the dorsum of the glans and then fuse ventrally to form the frenulum at the midline, the ventral surface of the glans is the last part of the penis to be covered by foreskin, so deficient perpetual development usually results in defective ventral prepuce as in cases of hypospadias and some cases of microposthia. The glans was partially covered by the foreskin only in the fetus at 13 weeks. Prepuce completely covering and fusing with the glans structure at around twenty-fourth week of gestation. It is generally accepted that normal preputial development is required for successful canalization of the glandular urethra, so the absence of the prepuce would result in an abnormal development of this part of urethra, and to be manifested as a hypospadias with a usual hooded prepuce.