The Male Reproductive System
To understand how reproductive hazards affect a man's ability to have healthy children, it is important to understand how the male reproductive system works.
The testicles have two important functions: they produce the hormone testosterone, which produces the deep male voice, beard, and sex drive; and they produce sperm.
After the sperm are made (in about 72 days), they are stored in the epididymis, the outer structure of the testicles. The sperm remain in the epididymis for about 15 to 25 days. While there, they mature and develop the ability to swim. If the sperm are not ejaculated, they eventually die and are absorbed by the body.
When a man ejaculates, the mature sperm cells move through the vas deferens (the tube cut in a vasectomy) and past the seminal vesicles and prostate gland. The seminal vesicles and the prostate provide most of the liquid in semen.
The semen is deposited in the vagina and the sperm must then swim through the cervix into the uterus and up into the fallopian tubes. If an egg is present, it is fertilized in the fallopian tubes. The fertilized egg then moves down to the uterus, where it attaches to the wall and continues to grow. If no egg is present, the sperm may live within the uterus for up to 2 days.
How Do Reproductive Hazards Affect the Male Reproductive System?
Number of Sperm
Some reproductive hazards can stop or slow the actual production of sperm. This means that there will be fewer sperm present to fertilize an egg; if no sperm are produced, the man is sterile. If the hazard prevents sperm from being made, sterility is permanent.
Reproductive hazards may cause the shape of sperm cells to be different. These sperm often have trouble swimming or lack the ability to fertilize the egg.