Gossypol--a new antifertility agent for males.

Gossypol is capable of inhibiting the fertility of male rats. On administration of gossypol the spermatids are damaged first. With the increase in dosage and duration of treatment the spermatocytes are also damaged. In the epidymis there are exfoliated spermatids and spermatocytes with numerous dead spermatozoa many of which had their heads and fails separated. The sperm count gradually decreases until azoospermia. Electron microscopic examinations reveal changes in the acrosomes and mitochondrial spiral sheath. Interstitial cells of the testis seemed to be unaffected. Over 4,000 healthy men have been on gossypol for more than 6 months. The antifertility efficacy evaluated by semen examination is 99.89%. Side effects are mild and of low incidence. A few of the subjects are found to be hypokalemic. However, it remains to be elucidated if gossypol is related to the development of hypokalemia.