within these organs. Once inside the target cells, testosterone is converted by means of an enzyme called 5α-reductase into the dihydrotestosterone (DHT). DHT mediates the androgen effect in these organs. Testes At nine weeks, male differentiation of the gonads and the testes is well underway. Internal changes include the formation of the tubular seminar Chris tubules in the Rete testis from the primary sex cord. Developing on the outside surface of each testis is a Phibro muscular cord called the gubernaculum. This structure attaches to the inferior portion of the testis and extends to the labial sacral fold of the same side at the same time, a portion of the embryonic mesonephric duct adjacent to the testis becomes attached and convoluted informs the epididymis. Another portion of the mesonephric duct becomes the ductus deferens. The seminal vesicles form from lateral outgrowths of the caudal and of each mesonephric duct the prostate gland arises from an Indo dermal outgrowth of the urogenital sinus the bulbourethral glands develop from outgrowths in the membrane-like portion of the urethra. The descent of the testes to its final location at the anterior abdominal wall, followed by the development of the gubernaculum, which subsequently pulls and translocates the testis down into the developing scrotum. Ultimately, the passageway closes behind the testis. A failure in this process can cause indirect inguinal hernia or an infantile hydrocoele. The testes descend into the scrotal sac between the sixth and 10th week. Dissent into this not occur until about the 28th week when compared and we know canals form and the abdominal wall to provide openings from the pelvic cavity to the scrotal sac. The process by which a testis to send is not well understood but it seems to be associated with the shortening of the gubernaculum, which is attached to the testis and extends to the inguinal canal to the wall of the scrotum as a testis to sense it passes to the side of the urinary bladder and anterior to the symphysis pubis. It carries with it the ductus deference, that is testicular vessels and nerves, a portion of the abdominal muscle, and lymph vessels. All of the structures remain attached to the testis and form what is known as the spermatic cord by the time the testis is in the scrotal sac, the gubernaculum is no more than a remnant of scar like tissue. External genitalia