The prostate gland is just below the bladder, behind the pubic bone and just in front of the rectum. The prostate wraps around the urethra, which is the tube that carries urine from the bladder to the penis.
The prostate helps to control the flow of urine. During sexual activity, the seminal vesicles that are attached to the prostate
produce a protein that mixes with prostatic fluid which forms semen. The tubes from the testicles carry sperm up to the prostate where sperm is mixed with the seminal vesicle and prostatic fluids. This fluid is ejaculated during orgasm through ejaculatory ducts that connect to the urethra.
Most men will experience some type of prostate problem during their lifetime. Men over forty-five may experience an enlargement of the prostate. While not a problem in itself, it is uncomfortable and can lead to more serious problems.
The prostate actually continues to grow throughout life, but grows very slowly after the age of twenty-five. Enlargement of the prostate gland is part of the normal aging process and usually does not become a serious problem until about age sixty.
Source: Prostate health network