Sperm are produced in the 
testes and move into the 
epididymis where they mature over a period of 10 to 14 days. Sperm are stored here and in the 
vas deferens where they can remain viable for several months. When ejaculation occurs muscle contractions of the vas deferens propel sperm into the 
ejaculatory duct where is is mixed with seminal fluid from the seminal vesicles. This fluid constitutes about 60% of the volume of semen. The sperm and seminal fluid continue through the prostate gland into the 
(prostatic) urethra. Here it is mixed with prostatic secretions which enter the urethra via many tiny prostatic ducts. Next the 
bulbourethral glands contribute fluid to the semen as it exits the prostate and continues through the urethra. Lastly muscles near the bulb of the penis help to propel the semen through the 
urethra out of the body.
Male Reproductive System
The male reproductive organs include the testes, the epididymis, the vas deferens, seminal vesicles, prostate, bulbourethral glands, scrotum and penis. Nearby structures are the bladder and rectum.
