There are, in fact, varying degrees of in, ranging from a slighdy lower than normal number of viable sperms to a total absence – a condition known as which results in sterility. A sterile man cannot father children. An infertile man father children, but his chances of doing so depend upon how far short of the ideal the quality of his sperm falls, and also how fertile his wife is. If, for instance, she has very regular periods (so that the time of ovulation can be predicted pretty accurately) and produces highly receptive mucus through which the sperms can swim easily into the , she may conceive with no difficulty at all. It might never even be realized that her husband is infertile. On the other hand, a less fertile woman may have just one child, or maybe none at all with such a man- although she might conceive comparatively easily with a fully fertile man.
Inin some men is caused by the failure of their testes to descend from near the kidneys – where they first develop in the embryo – to the scrotum outside the body cavity. This means that the sperms are being continually exposed to body temperature which damages them. Unless the testicles can be brought into the scrotum, by surgery if necessary, by not later than two to three years of age the patient will probably be infertile. And if the testicles remain undescended puberty he will most certainly be sterile. A common cause of infertilitv is a varicocele. This is an enlargement of the veins draining the testicles, quite often the left testicle. The varicocele is caused by a defect of the valves in the veins which leads to a pooling of blood. This affects the temperature regulation in the testicles, which interferes with the production of sperms.
Infections can also impair fertility. Venereal disease and tuberculosis are two extreme examples, but even a relatively common disease like mumps can present a problem, especially if contracted after puberty. The mumps virus can attack the testes, causing an acute infection known as orchitis. Large areas of the affected testicle, including the delicate seminiferous tubules where sperms are manufactured, may be destroyed by the inflammation and replaced by scar tissue, leading to permanent damage.
Sometimes infertility can be caused by a congenital or genetic defect This can result in a severe reduction in the number of sperms developing in the testicles, or can affect the ability of the testicles to make any sperms at all. This is a permanent condition, for which there is no cure at present.
Total infertility – that is to say sterility – can result from either a failure to produce any sperms, or from a blockage of the ducts through which sperms pass to be ejaculated. In a very few cases, sterility can be caused by both these factors. This particular blockage can be caused either by defective development or infection. Where tuberculosis or venereal disease is the cause, sometimes the infection results in inflammation of one of the ducts; in the process of repairing the damage, the body forms scar tissue that can block or destroy the affected duct.
Heavy smoking, excessive drinking and obesity may be causes or low sperm count in some men, as may addictive drugs, and a number of drugs used to treat diseases such as ulcerative colitis, inflammation of the small intestine and high blood pressure.
One of the theories attracting attention is that infertility could be the result of an auto-immune reaction. In some men their bodies are manu-facturing antibodies- part of the body’s defence system, the function of which is to attack and destroy invading germs – to their own sperms. Doctors don’t know why this happens, but they think it could be quite a common cause of otherwise unexplained infertility.
A small percentage of infertility and sterility in men is due to a hormone deficiency. Blood tests can be carried out to determine whether or not this is a factor. The pituitary gland manufactures the(follicle-stimulating hormone) and L(luteinizing hormone), collectively called the LH stimulates the testicles to produce the male sex hormone which is essential for the manufacture of sperms; FSH stimulates the germs cells to produce sperms. Overproduction of the gonadotrophins causes severe damage to the structure of the testicles, making them incapable of responding to stimu-lation. A blood test will show if the gonadotro-phins are present in normal amounts or, if not, whether they are deficient or excessive.
Where infertility and sterility are the result of a hormonal defect the problem can be solved by hormone replacement therapy. For instance, a patient with a defective pituitary gland which isn’t producing enough FSH or LH can be injected with human menopausalgonadotrophin (HMG) which is obtained from the urine of postmenopausal women, and human chorionic gonadotrophin (HCG), obtained from the urine of pregnant women. Another hormone used to treat men with a low sperm count is clomiphene, which is also used to treat female infertility. This usually stimulates the pituitary gland to secrete more gonadotrophin, but in only 20 to 30 per cent of cases will it increase the sperm count. Because it takes three months to manufacture sperms, hor- mone therapy is a lengthy process, involving treatment over a period of many months.
Is it true that wearing very tight clothes can lower a man’s fertility? Yes it is, because infertility can be caused by keeping the testicles too warm. The ideal tem-perature for sperm production is 2.2 degrees lower than that of the abdominal cavity. The scrotal sac, which envelopes the testicles, acts as the thermostat. The sac is a multi-layered pouch laced with sweat glands and muscles. When it’s cold these muscles contract, pulling the testicles closer to the warmth of the body, when it’s hot they relax, pushing the testicles away from the body. The sweat glands also help control the temperature. So men who habitually wear jock straps or very tight-fitting jeans, work in very high temperatures, or who sit for long periods -such as long-distance lorry drivers- can become infertile, because they are preventing these natural temperature controls from operating.