The prostate gland is a male reproductive organ that is about the size of a walnut, found at the base of the bladder. The urethra is a thin tube that allows the passage of urine out of the penis. It runs through the prostate gland. Fluid produced by this gland helps to protect and feed sperm, which come from the seminal vesicles via the ejaculatory ducts into the urethra.
The prostate undergoes two main growth spurts. The first is fuelled by sex hormones made by the testicles during puberty. This prompts the gland to reach an average weight of 20 grams in adulthood. For reasons that are unclear, the second growth spurt begins when men are in their 30s. The prostate continues to enlarge with age to an average weight of 40 grams in men in their 70s. Many men experience urinary changes as they age, which may be caused by inflammation or enlargement of the prostate gland. An enlarged prostate gland, however, does not always cause urinary problems. Troublesome urinary symptoms are rarely symptoms of prostate cancer.