Abstract
Morphologic comparisons of the live and dead sperm population gives information concerning non-lethal and lethal abnormalities. Many of the abnormalities of the sperm heads and midpieces and in particular enlarged heads belong to the latter group. On the other hand, tapering of the head, cytoplasmic droplets and abnormal tails have littel lethal significance. Depletion of the extra-gonadal sperm reserve does not affect the morphology of neither the living nor the dead spermatozoa. This indicates that no significant abnormalities develop after sperm maturation within the epididymis. Cyproterone acetate was shown to affect midpieces and fails of the living spermatozoa within two weeks of treatment indicating an effect on the epididymal level, whereas abnormal heads increase after four weeks indicating an effect on the germinative epithelium, not before the spermatid stage.