The ductus deferens (also called the Vas deferens)is part of the male anatomy that transports sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. 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 (0.98 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.