The Male Reproductive System

2005-02-21 13:23

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.

Sperm Shape
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.

Sperm Transfer
Hazardous chemicals may collect in the epididymis, seminal vesicles, or prostate. These chemicals may kill the sperm, change the way in which they swim, or attach to the sperm and be carried to the egg or the unborn child.

Sexual Performance
Changes in amounts of hormones can affect sexual performance. Some chemicals, like alcohol, may also affect the ability to achieve erections, whereas others may affect the sex drive. Several drugs (both legal and illegal) have effects on sexual performance, but little is known about the effects of workplace hazards.

Sperm Chromosomes
Reproductive hazards can affect the chromosomes found in sperm. The sperm and egg each contribute 23 chromosomes at fertilization. The DNA stored in these chromosomes determines what we will look like and how our bodies will function. Radiation or chemicals may cause changes or breaks in the DNA. If the sperm's DNA is damaged, it may not be able to fertilize an egg; or if it does fertilize an egg, it may affect the development of the fetus. Some cancer treatment drugs are known to cause such damage. However, little is known about the effects of workplace hazards on sperm chromosomes.

If a damaged sperm does fertilize an egg, the egg might not develop properly, causing a miscarriage or a possible health problem in the baby. If a reproductive hazard is carried in the semen, the fetus might be exposed within the uterus, possibly leading to problems with the pregnancy or with the health of the baby after it is born.


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