Abnormal axonemes in sperm of fertile men

Sperm of 20 men aged 20-44 years was analyzed for motility and tail deformities in a Makler chamber and for axoneme abnormalities by transmission electron microscopy. In the quantitative analyses, 12.5 +/- 5.5% deformed tails at the light microscopic level and 24.4 +/- 7.7% abnormal axonemes in the principal piece. This high incidence of abnormalities in the sperm of fertile men indicated that micrographs of abnormal axonemes alone could not be used to imply the pathogenesis of infertility or sperm immotility without statistical comparison with a control group. Axoneme abnormalities were subdivided into three types. There was an asymmetry of abnormal axoneme types along the length of the sperm tail. Based on this asymmetry and on images of longitudinally sectioned sperm, the different types of abnormal axonemes most likely represented a single process of doublet microtubule detachment and foldback. Correlation of electron and light microscopy suggested that axoneme foldback progressed to focal tail defects and subsequent collapse. The presence of these abnormalities in fertile donors indicated that they were part of a normal process of axoneme instability in human sperm.