The prostate is a walnut-shaped gland that is located below the bladder and surrounds the urethra of males. In a normal adult man, it weighs two thirds of an ounce and measures, at most, 1.6 inches along its transverse axis, 1.2 inches along its vertical axis, and 0.8 inches along its horizontal axis. Its function is to produce a fluid that makes up approximately 30 percent of the volume of semen. This fluid, containing citric acid, calcium, and enzymes, probably improves sperm motility (ability to swim) and fertility. Moreover, the fluid secreted from the prostate includes zinc, which scientists theorize protects against genital-tract infections.

The prostate is peculiar to the male but related in tissue type to the female breast. It is made up of a well-muscled capsule within which are found 30 to 50 saclike glands. These glands produce the prostatic fluid, without which a man would almost certainly be infertile. The tissue within the glands is folded, allowing for expansion and storage as the fluid is produced. After a male reaches puberty, the sacs begin producing a small amount of fluid each day, which is normally voided with the urine if he has no sexual relations. Not all the prostate’s functions are known, but its primary purpose seems to be to produce the fluid that nourishes millions of sperm cells and provides them with a medium to swim in. Thus, it is vital for a man’s fertility. It can, though, also cause him problems as he gets older.