Vas deferens

The vas deferens (Latin: "carrying-away vessel"; plural: vasa deferentia), also called ductus deferens (Latin: "carrying-away duct"; plural: ductus deferentes), is part of the male reproductive system of many vertebrates; these vasa transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation.

Structure

There are two ducts, connecting the left and right epididymis to the ejaculatory ducts in order to move sperm. Each tube is about 30 centimeters (1 ft) long (in humans), 3 to 5 mm in diameter and is muscular (surrounded by smooth muscle). Its epithelium is lined by stereocilia.

They are part of the spermatic cords.

Blood supply

The vas deferens is supplied by an accompanying artery (artery of vas deferens). This artery normally arises from the superior (sometimes inferior) vesical artery, a branch of the internal iliac artery.

Function

During ejaculation, the smooth muscle in the walls of the vas deferens contracts reflexively, thus propelling the sperm forward. This is also known as peristalsis. The sperm is transferred from the vas deferens into the urethra, collecting secretions from the male accessory sex glands such as the seminal vesicles, prostate gland and the bulbourethral glands, which form the bulk of semen.