Embryology of the human genital tract

Abstract

Before sexual differentiation begins at 7-8 weeks of gestation, the urogenital ridge develops on the posterior abdominal wall from the intermediate mesoderm. The Wolffian (mesonephric) and Műllerian (paramesonephric) ducts form and migrate caudally to the cloaca, while the germ cells migrate from the yolk sac into the bi-potential gonad as the mesonephros regresses. At sexual differentiation, AMH, testosterone and INSL3 are secreted from the testis to control ductal development, external genital virilisation and descent of the testis into the scrotum.