The sperm are manufactured in the testicles which lie within the scrotum. Sperm production requires a slightly lower temperature than the rest of the body, this is possibly the reason why testes hang in the scrotum.
The testes are made up of long loops of fine tubes (called seminiferous tubules). Sperm production begins with immature sperm cells that grow and mature within the seminiferous tubules. The production of sperm begins at puberty and continues throughout a man's life into old age - the production of sperm is stimulated by the hormone FSH. It takes about 70 days for the sperm to mature. The testes also contain Leydig cells which produce the male hormone testosterone and Sertoli cells which provide support and nutrition to the developing sperm.
Each seminiferous tubule ends in a structure called the epididymis, which lies above the testis. The epididymis is a single tube, highly coiled, and approximately 5 meters long. The sperm are stored in the epididymis for up to two weeks where they mature and acquire motility.
The vas deferens is a hollow tube that connects the epididymis to the urethra. During ejaculation, contractions of the vas propel the sperm into the urethra.
The urethra is a muscular pipe that connects the bladder to the outside via the penis, through which urine and sperm pass out of the body. The sperm enter the urethra at the time of ejaculation. Semen and urine never mix in a healthy man because the bladder sphincter contracts during orgasm thus, closing down the exit from the bladder to the urethra.
The prostate gland is a small gland that lies below the bladder and fits around the urethra.
The seminal vesicles (two reservoirs that connect to the vas deference) lie on either side of the prostate.
Fluids from the prostate gland (60% of the seminal fluid volume) and seminal vesicles (30% of the seminal fluid volume) form part of the seminal fluid, in which sperm are bathed. The seminal fluid contains chemicals and nutrients that are essential to the sperm health.