prostate gland, gland that is part of the male reproductive system. It is an organ about the size of a chestnut and consists of glandular and muscular tissue. It is situated below the neck of the bladder, encircling the urethra. The prostate produces a thin, milky, alkaline fluid that is secreted into the urethra at the time of emission of semen, providing an added medium for the life and motility of sperm. It is probable that prostatic fluid enhances fertility since the fluid flowing from the testes and seminal vesicles is acidic and sperm are not optimally mobile unless their medium is relatively alkaline.
In men over 50 enlargement of the prostate (benign prostatic hypertrophy) is common. Sometimes the result is pressure on the urethra and bladder, which interferes with urination, precipitating urinary retention and kidney disease. Balloon dilatation of the urethra and medication with alpha blockers, finasteride (Proscar), and saw palmetto extract (an herbal supplement) have joined traditional surgical removal of the prostate (prostatectomy) as therapies. See also prostate cancer, prostatitis.
See J. P. Blandy and B. Lytton, The Prostate (1986).
More on prostate gland from Infoplease:
See more Encyclopedia articles on: Anatomy and Physiology