Sperm Production and the
Role of Male Hormones
As in women, the male’s pituitary gland produces follicle stimulating
hormone (FSH) and luteinizing hormone (LH). LH stimulates cells located in the
testes to produce testosterone, the hormone associated with male
characteristics and responsible for sperm production and maturation.
Testosterone also is responsible for male potency, as it stimulates the sex
drive and the male’s ability to achieve and maintain an erection. Male FSH
supports the development of sperm in the seminiferous
tubules, tiny tubes located in the testes. The sperm carry the male’s
genetic traits, which meld with the genetic material in the female’s egg
during fertilization.
New, round-shaped sperm cells are produced in a layer along the tubule wall.
Still immature, they move into a central passageway to begin their travel
through the epididymis,
a 10-foot-long tube attached to each testes. From the epididymis, the sperm
move through one of two 14-inch tubes called the vas
deferens (or vas). Each vas is connected to a small pouch, the seminal
vesicle, located behind the bladder. Both lead to the prostate
gland, through which the semen enters the urethra. Carried by seminal
fluid produced mostly by the prostate and seminal vesicles, the sperm then
travel along the urethra to the end of the penis during ejaculation.
Sperm take approximately three months to fully mature, during which the round
cell becomes elongated and sprouts a tail-like structure. Following
ejaculation into the vagina, the tail provides the thrust the sperm need to
swim up and fertilize a waiting egg. Healthy sperm can live up to two days in
the female’s body, making fertilization possible not only during, but also
around the time of ovulation. Whether this goal is achieved depends in large
part on the volume, quantity and quality of sperm available. These factors are
assessed during semen
analysis, an important part of the male infertility work-up.
