The prostate is a walnut-sized gland located between the bladder and the penis and in front of the rectum. The urethra, the tube which carries urine from the bladder and out of the body through the penis, passes through the center of the prostate. The microscopic nerves that control erection are attached to both sides of the prostate as they extend to the penis. The prostate is not a vital organ; however, it is surrounded with lots of small and sensitive nerves and blood vessels that can be damaged as a result of the disease and its treatment. In some ways, it functions as "Grand Central Station" for the male reproductive and urinary systems where urine and semen must pass through the prostate to leave the body. Its importance is less related to what it does than to the problems that it creates when something goes awry.

The Prostate's Role in Reproduction

The primary function of the prostate is the production of seminal fluid, a milky substance that nourishes sperm (seminal vesicles, attached to the prostate, contribute nutrients as well). Sperm passes to the prostate by traveling through the vas deferens, tubes originating from the testes. The semen, a mixture of seminal fluid and sperm, is ejaculated during orgasm through a connection to the urethra called the ejaculatory ducts.

Anatomy of the Prostate

The prostate is divided into five zones:

Peripheral zone - located in the rear part of the prostate near the rectum and which contains three-fourths of the glands in the prostate and is where most prostate cancer occurs.
Central zone - involved in the connection of the seminal vesicles to the prostate, and which contains most of the rest of the organ's glands.
Anterior zone - primarily smooth muscle tissue, is located in the front part of the prostate.
Transition zone - the zone that enlarges with "benign prostatic hyperplasia" (BPH), a noncancerous enlargement of the prostate.
Pre-prostatic tissue - contains muscles that help prevent semen from flowing backward into the bladder during ejaculation.