Male Genital System
Male Genital System

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- embryology of male gonad and genital ducts → see section on genitourinary embryology - embryology of germ cells and gonads, day 8 through 12th week (first trimester) - primordial germ cells (mesodermal origin) are sequestered in caudal wall of yolk sac, and during fifth week migrate to the gonadal ridges, located between the vertebral column and the mesonephros (primitive kidney) - in males, germ cells in testes become surrounded by cells of the medullary sex cords to become spermatogonia in seminiferous tubules - spermatogonia = spermatozoa - forming cells of testes - in the embryo, submesothelial mesodermal cells (called medullary sex cords) surround spermatogonia, becoming seminiferous tubules, internally lined by Sertoli cells (also of mesodermal origin), and the ends of the seminiferous tubules retain connection to the testicular subsurface at the rete testis - some mesodermal cells between tubules become interstitial cells of Leydig - gonadal ridges (sexually indifferent gonads) - descend caudally in the retroperitoneum, by differential growth of the embryo, protruding forward and obtaining a capsule of peritoneum ( mesothelium) - in females, become ovaries - in males, become testes, “dragging” along blood supply (testicular artery and vein) as well as their duct [Wolffian (mesonephric) duct], as they ‘migrate’ into scrotal sac - from pelvis, testes are pulled through the inguinal canal and into scrotum by myofibroblastic contractions in the ligament of the gubernaculum, attached to base of s crotum, while being pushed by increasing intra - abdominal pressures - testis comes to rest in floor of processus vaginalis, a diverticulum of peritoneum - mesotheilial peritoneal epithelium lines scrotal cavi ties and surface of testes - mesothelial surface of testis is called tunica vaginalis - tunica vaginalis on the testicular surface overlies the dense fibrous capsule of the testis, called tunica albuginea © Stroma of testis Sperm - atogonia