Abnormalities

Infertility In Men

What causes abnormalities?

Infertility can result from many different factors. The specific cause of sperm abnormalities cannot be established in most cases. It may be the end result of one or a combination of factors that include chronic illness, malnutrition, genetic defects, structural abnormalities, and environmental factors. Partial obstruction anywhere in the long passages through which sperm pass can reduce their sperm counts.

Genetic Factors

Aside from inherited diseases that cause infertility, certain genetic factors may play a large role in many cases of male fertility. Much research has focused on a group of deletions in certain regions of the Y chromosome known as AZF. This defect appears to be a major genetic cause of severe male infertility and may be responsible for between 2% and 21% of cases of inadequate sperm. Another area of genetic research targets the gene for apolipoprotein B, which is known to play a key role in cholesterol metabolism, may also be a factor in infertility. It should be noted that genetic mutations may occur not only through inheritance but also from environmental assaults.

Environmental Factors

Exposure to Chemicals. Some experts believe a decline in fertility may be due to the exposure of male fetuses during pregnancy to environmental chemicals with o estrogen-like effects. Such chemicals include pesticides, such as DDT, aldrin, dieldrin, PCPs, dioxins, and furans. Although tests of single chemicals containing oestrogen have reported little dangers, other studies indicate that combinations of estrogen-containing chemicals may be very harmful. Overexposure to oestrogen reduces the number of Sertoli cells (the cells necessary for the initial development of sperm). In addition to the effect on fertility, some researchers believe such overexposure may also contribute to testicular cancers. Aside from the o estrogen-like chemicals, other environmental pollutants or stresses can affect sperm quality and count, although the effects of most have not been proven.

Oxygen-Free Radicals

High levels of oxygen-free radicals (damaging particles that are naturally released and are produced by certain environmental toxins) have been found in the semen of 40% of infertile men. Such particles are known to injure cells, including causing genetic changes that increase the risk for heart disease and cancer. Evidence now strongly indicates that they can also damage sperm.

Exposure to Heavy Metals

Trace amounts of metals in semen seem to inhibit the function of enzymes contained in the acrosome, the membrane that covers the head of the sperm. Chronic exposure to heavy metals such as lead, cadmium, or arsenic can affect sperm quality. The effect on fertility of small particles of metals released into the air from incinerators or manufacturing plants or present in urban air pollution is not yet known.

Radiation Treatment

Radiation treatments and x-rays affect any rapidly dividing cell, so cells that produce sperm are quite sensitive to radiation damage. Cells exposed to significant levels of radiation may take up to two years to resume normal sperm production, and, in severe circumstances, may never recover.

Highlights

Infertility