The ductus deferens (vas deferens) is the continuation of the duct of the epididymis.

The ductus deferens:

• Has relatively thick muscular walls and a minute lumen, giving it a cord-like firmness.

• Begins in the tail of the epididymis, at the inferior pole of the testis.

• Ascends posterior to the testis, medial to the epididymis.

• Is the primary component of the spermatic cord.

• Penetrates the anterior abdominal wall via the inguinal canal.

• Crosses over the external iliac vessels and enters the pelvis.

• Passes along the lateral wall of the pelvis, where it lies external to the parietal peritoneum.

• Ends by joining the duct of the seminal gland to form the ejaculatory duct.

During the pelvic part of its course, the ductus deferens maintains direct contact with the peritoneum; no other structure intervenes between them. The ductus crosses superior to the ureter near the posterolateral angle of the urinary bladder, running between the ureter and the peritoneum of the ureteric fold to reach the fundus of the bladder. The relationship of the ductus deferens to the ureter in the male is similar, although of lesser clinical importance, to that of the uterine artery to the ureter in the female. Posterior to the bladder, the ductus deferens at first lies superior to the seminal gland, then descends medial to the ureter and the gland. Here the ductus deferens enlarges to form the ampulla of the ductus deferens before its termination.

The tiny artery to the ductus deferens usually arises from a superior (sometimes inferior) vesical artery, and terminates by anastomosing with the testicular artery, posterior to the testis.

Veins from most of the ductus drain into the testicular vein, including the distal pampiniform plexus. Its terminal portion drains into the vesicular/ prostatic venous plexus.