The question of toxicity to the gonads: testes and ovaries is a point of concern for all those who work with infertility. This toxicity is determined by any chemical agent, physical or biological agent that can alter the endocrine system or spermatogenesis, causing changes in reproductive physiology. The interruption of the normal biological process may occur by direct action of the agent, or indirectly through their metabolites. In addition to these, factors such as stress, age and weight should be taken into account:
Patients who did not drop one or two testicles to the scrotum before birth usually have lower quality sperm, regardless of the realization early surgical correction. Other testicular factors that can determine a lower quality of semen testicular pain would be stronger in childhood related to episodes of testicular torsion, infection, venereal diseases or medication use. Situations that cause fever, such as systemic infections, can temporarily alter spermatogenesis.
There are many causes of pathologies that can lead to a change in sperm quality. Infectious diseases (mumps, tuberculosis, leprosy and sexually transmitted diseases), chronic diseases (diabetes mellitus, atherosclerosis, kidney failure, lupus erythematosus, hypertension, etc…) Tumors such as pituitary adenoma, craniopharyngioma and others. Patients with thalassemia major develop infertility by the deposition of iron in the pituitary gland and testicles. Diabetes mellitus can cause damage neuropathic, leading to retrograde ejaculation (toward the bladder instead of the urethra).
There are a large number of substances that are toxic to sperm production and function. Several types of medications (some antibiotics, chemotherapy, hormones and anabolic steroids), drugs (marijuana, cocaine, alcohol, cigarettes, heroin, crack, etc…) Occupational and environmental factors (heat, light, electromagnetic radiation, etc…) Agents pollutants, industrial and environment have been related to changes in fertility, as well as stress. With respect to drugs and illicit drugs, one must be careful to identify those that are known to have negative effect on spermatogenesis.
Infectious diseases cause partial or total obstruction of the seminal track and / or gonad histological changes. Estrogens in the environment (pesticides and herbicides) and diet (plants, cereals, fruits, vegetables and oilseeds) have been widely studied, mainly due to higher incidence of malformations of the genital tract in the last 50 years, and suspicions of the decrease sperm count.
The increase in testicular temperature produces a decrease in quality and quantity of sperm and also dysfunction of the epididymis, as shown in occupational exposure to heat (bakers, confectioners, firefighters, welders, etc.).. The effect of prolonged exposure to heavy metals (cadmium, mercury, boron) can also lead to changes in spermatogenesis, testicular fibrosis, and hormonal changes.
Smoking can lead to decreased sperm production and worsening of their morphology and motility. Several pesticides have toxic effects on the testes changing fertility and sexual function. Anesthetic gases such as nitrous oxide and halothane, promote reduced production of spermatozoa and chromosomal aberrations.
A varicose veins in the testicles is the clinical condition most commonly found, accounting for 18% of cases, however, is only considered as a cause of infertility when combined with sperm abnormal patterns, which occurs in about 10% of the time . There are several theories that attempt to explain the seminal and testicular changes resulting from these veins, however it is unclear why some patients with varicose are fertile at all, or because 20 to 30% of patients undergoing treatment show no improvement in semen parameters.
In many cases, the cause of infertility is not defined. Studies have shown a high incidence of structural and numerical changes of chromosomes in infertile men compared to fertile men. Most of the changes in sex chromosomes found in azoosperm patients (absence of sperm in the ejaculate). Ten to 15% of patients with non-obstructive azoospermia have deletions in their Y chromosome (absence of fragments on the Y chromosome).
The congenital absence of channels that communicate the testicle to the urethra and cystic fibrosis are other genetic causes that interrupt the transport of sperm to the urethra, without interfering with its production. These patients produce sperm, but they are not ejaculated.
Situations that would impede the function of sperm, such as antibodies, are found in about 5% of men; however, the role of anti-sperm antibodies remains very controversial. The stress probably decreases fertility, but it is difficult to know how to measure and determine their level of participation.
There is no evidence that the man's age, by itself, predisposes to infertility (as opposed to women), although other diseases that accompany aging may predispose to infertility, and there seems to be a decrease in semen volume and concentration sperm over the years. Chronic malnutrition causes hormonal changes and, along with protein deficiency interferes with fertility.
The excess body weight and fat distribution appear to be minor effects on men than on female fertility.