Inhibition of spermatozoa maturation in rhesus monkey by cyproterone acetate.

The morphology of spermatozoa from the initial segment, caput, corpus and cauda epididymides of normal and cyproterone acetate-treated animals was studied using light and scanning electron microscopy to understand the changes taking place during spermatozoa maturation. A progressive and significant decrease in the percentage of spermatozoa that retained the cytoplasmic droplet and a shift in its position from proximal end of the midpiece to its distal end were seen during epididymal transit; these events were inhibited in cyproterone acetate-treated animals. A large percentage of spermatozoa from the initial segment and the caput epididymides showed coiling of the spermatozoa tail which involved the midpiece, principal piece and the endpiece. The percentage of spermatozoa that showed the coiled tail decreased; a gradual straightening of the spermatozoa tail with less complex types of coiling was also seen during epididymal transit. Cyproterone acetate reversed these changes occurring during maturation. These results indicate that spermatozoa maturation in the rhesus monkey, occurring between the corpus and cauda epididymides, is an androgen-dependent event.