There are two of these ducts, which are tubes surrounded by smooth muscle. They connect the left and right epididymis to the ejaculatory ducts in order to move sperm. Each tube is about 30 centimeters long. During ejaculation the smooth muscle in the wall of the vas deferens contracts. That pushes the sperm toward the penis. The sperm go from the vas deferens into the urethra. Other male sex glands push out at the same time.