The scrotum and testes

TESTIS AND SCROTUM.
ANATOMY OF THE TESTIS
The testes develop in the retroperitoneum below the kidneys in early fetal life. About the same time as the wolffian duct becomes the epididymis and vas deferens,also at that time,the precursor of the gubernaculum develops as a fold of peritoneum. The processus vaginalis starts as a dimple of peritoneum in about the 10th week of gestation and precedes the testis in its journey through the abdominal wall down to the scrotum. The fully developed gubernaculum contains muscle fibers but it is still not clear what part it plays in testicular descent. Maternal chorionic gonadotrophin stimulates growth of the testis and may stimulate its migration. Imperfectly developed testes tend to descend incompletely.
The epididymis extends as a fleshy strip on the posterior aspect of the testis and is palpable as a separate structure. The vas deferens takes its origin from the epididymis.
It can be felt above the testis as a firm tubular structure entering the external inguinal ring.
In the inguinal canal, the vas deferens is invested by the cremasteric muscle along with the other components of the spermatic cord.