New aspects of the aetiology of male fertility disorders.

Classification of male fertility disorders should take into account the cause and severity of a disturbance as well as its effect on the fertilizing capacity of spermatozoa. A reasonable approach is the analysis of sperm morphology according to the Düsseldorf classification, which is based on defects of spermatid differentiation. The kind and frequency of malformed spermatozoa allow conclusions about basic testicular and epididymal disorders, which will facilitate the detection of epididymal sperm motility disturbances and, therefore, initiation of causal treatment. The effect of inflammatory processes on fertility depends on the site of inflammation. In addition, the necessity for varicocele treatment can be determined more exactly under consideration of sperm morphology and hormonal tests. So far, irregular chromatin condensation as a cause of disturbed male fertility has not been attributed to genetic reasons, whereas microdeletions of the Y chromosome are increasingly being discussed. Both the role of oxygen radicals and the significance of environmental factors need to be investigated in the future.