Vas Deferens

The vas deferens is a thick-walled tube about 18 in. (45 cm) long that conveys mature sperm from the epididymis to the ejaculatory duct and the urethra. It arises from the lower end or tail of the epididymis and passes through the inguinal canal. It emerges from the deep inguinal ring and  passes around the lateral margin of the inferior epigastric artery. It then passes downward and backward on the lateral wall of the pelvis and crosses the ureter in the region of the ischial spine.

The vas deferens then runs medially and downward on the posterior surface of the bladder. The terminal part of the vas deferens is dilated to form the ampulla of the vas deferens. The inferior end of the ampulla narrows down and joins the duct of the seminal vesicle to form the ejaculatory duct.