In both sexes the internal genital structures arise again from bipotent anlagen, the Wolffian ducts and the Müllerian ducts. Under the influence of AMH secreted from the Sertoli cells of the testes during the critical period, the Müllerian ducts regress. So in the typical male development, the differentiation and growth of the uterus, upper third of the vagina, and fallopian tubes is actively sup pressed. AMH acts through the AMH II receptor in the Müllerian duct mesenchyme.
In contrast, the Wolffian ducts develop under the influence of testosterone, giving rise to the epididymis, the seminal vesicles, and some parts of the prostate. The human fetal testes synthesize testosterone from the eighth week of gestation. The timing of development for testosterone- dependent structures, however, is very distinct. The prostate forms around the tenth to thirteenth week of gestation, while the seminal vesicles develop later, around week 14– 16. Testosterone initially stabilizes the Wolffian ducts and elongation and convolution of the cranial end leads to formation of the epididymis, the middle portion forms the vasa deferentia and the caudal part differentiates into the seminal vesicles. The prostate develops from the urogenital sinus, which arises in humans around the seventh week of gestation from the cloaca. Androgens, namely testosterone, will lead to differentiation into zonal subdivisions to form the prostate. Female development does not depend on hormonal influences to mediate differentiation. In the absence of AMH, the Müllerian duct will differentiate into the uterus, fallopian tubes, cervix, and upper vagina. The lack of androgens causes the Wolffian duct to regress.
Again, the male development is dominant and hormone de pendent. In some types of DSD with high amounts of testosterone formed in the adrenal, such as 21- hydroxylase deficiency leading to congenital adrenal hyperplasia, there are residues of prostate tissue even in 46,XX individuals.
