The Prostate is a walnut-shaped gland, about one and a half inches long. Located directly beneath the bladder, the prostate completely surrounds the urethra, the channel running from the bladder through the penis, which carries both urine and semen from the body.

The primary function of the prostate gland is to produce part of the fluid that makes up semen. During ejaculation, muscles in the prostate contract to push the prostatic fluid through tiny ducts into the urethra, where it mixes with sperm and other fluid.