What is the prostate?

The prostate is a small, walnut-sized gland that lies at the base of the bladder in men. It consists of two symmetrical lobes and surrounds the first part of the tube (the urethra) that carries urine from the bladder to the penis. The urethra also carries semen, which is the fluid containing sperm. The prostate is coloured orange in the diagram.

Anatomy of the male reproductive organs, showing the position of the prostate.