The sperm are carried from the two testicles by a tube called vas deferens. The testicles are located in two sacs on either side in the scrotum. The scrotum is the hanging section that is behind the penis. The vas is about 1-2 mm in diameter and is about 25 cm long. It climbs from the testicles and travels to the side of the abdomen and goes round to open at the base of the bladder into the prostate gland. The ejaculatory duct opens into the upper section of urinary tube called the urethera. Normally the sperm passes out of this opening and are propelled by the mascular action of the perineal muscles through the penis. The volume of an ejaculate can vary from 2 to 5 ml and it usually contain between 40 to 120 million sperms/ml. Although the sperms are produced in the testicles but the bulk of the fluid comes from the prostate gland.