Effects of microquantities of cyproterone acetate released through silastic capsules on the histology of the epididymis of the rat

The histological changes in the epididymis of rats exposed to microquantities of cyproterone acetate released from subcutaneously implanted Silastic capsules are recorded. A gradual reduction in the height of the epithelium, depletion of secretory granules, vacuolation of cells and nuclear pycnosis were observed in the caput and cauda epididymides at 4 months after implantation of the capsules. These degenerative changes reached their optimum at 6 months but returned to normalcy 15 days after removal of the capsules. Stainability of the acrosomes of the spermatozoa with PAS decreased significantly 4 and 6 months after implantation of the capsules; such epididymal spermatozoa were non-motile and non-viable. These results demonstrate a clear dissociation of the dose of antiandrogen needed to cause selective inhibition of epididymal function without interference with libido or the functions of the testes and accessory glands and indicate a new approach to control of fertility in the male