The male reproductive system consists of both internal and external components. Internally, it includes the testes, epididymis, ductus deferens, seminal vesicles, ejaculatory ducts, prostate and part of the urethra. Externally it includes the scrotum and penis. Sperm are produced in the testes and travel through the epididymis, ductus deferens and ejaculatory duct to mix with fluids from the seminal vesicles and prostate to form semen, which is ejaculated through the urethra. The scrotum houses the testes and maintains the optimal temperature for sperm production.