[Electron microscopy findings in human spermatozoa with flagellar defects].

Spermatozoal motility disorders must be interpreted with reference to whether the flagella are intact or impaired. A new classification of alterations of midpiece and flagellum includes a shaft disturbance that is increasingly often observed and can be recognized by light microscopy. Electron microscope examinations have shown that missing or poorly developed outer dense fibres are one cause of this flagellar disorder. As suitable longitudinal sections are rarely obtained in transmission electron microscopy, the negative staining technique was used in addition for this purpose. This method was found to be most suitable for an exact analysis of the periaxonemal structures of the sperm flagellum. Consideration of this hitherto unknown flagellar disturbance is important, because various therapeutic approaches have had little success so far and patients should be referred in good time for other gynaecological or andrological treatments.