The physiology and physiopathology of the male sexual glands

Abstract

During the formation of the embryo, the first sexual structures to develop are the fetal testes. This is followed by differentiation of the genital tracts and accessory organs from a dual set of sex ducts and from common primordia. The testis is probably important in the differentiation of the genital tract in the male by the elaboration of hormonal factors, JOST. The hormonal theory of differentiation is supported by the fact that ablation of the genital ridge in placental animals results in a feminine differentiation in the fetus whether the removed tissue was ovary or testis. If the testis is removed after sex differentiation has begun, however, it proceeds in the development of male genitalia. From these observations, it is concluded that the fetal testicular hormone has a stimulative effect on the Wolffian duct and common primordia and an inhibitory action on the Mullerian structures. Presence of testicular hormone has not been detected in the very young embryo during the critical period of sex diiferentiation but androgens have been extracted from sex differentiated bovine fetal testis and fetal rats. The fetal testicular hormone produced during sexual differentiation resembles adult androgenic hormone in its ability to stimulate the development of male organs (Wolffian duct, urogenital sinus and external genitalia). However, the adult androgenic hormone lacks the ability to suppress the development of the Mullerian duct system. It may be that more than one hormone is elaborated by the fetal testis. The cellular origin of testicular hormone is not known. Large numbers of interstitial cells appear in the testis late in embryogenesis that are similar to Leydig cells. These are apparently stimulated to develop by maternal gonadotropins. Their presence in the fetal testis suggests that androgenic hormone may be secreted. This may be similar to adult testicular androgenic hormone and may participate in the final sexual development and descent of the testis into the scrotum.The elaboration of a fetal testicular hormone may be controlled by the hypophysis. Decapitation in the rabbit prior to the stage of sex differentiation produces sexual modification. This is not so in the mouse and rat. Human anencephali!) monsters are females in the great majority, PERRIN. However, there is no evidence in man that hypophyseal control is present.The germinal epithelium begins to develop during the fifth and sixth weeks of embryonic life. At first a superficial layer of cells separates from a thickening The physiology and physiopathology of the male sexual glands 585 of the peritoneum near the urogenital ridge to form the germinal epithelium. These ridges of germinal epithelium contain primordial germ cells which are isosexual. The germ cells lie within a mass of proliferating epithelium. They then separate and begin to branch into cords. By the seventh week, the differentiation has progressed sufficiently to distinguish testicular from ovarian tissue.The testis cords converge in a radial fashion to form the mesorchium which soo...