Contraceptive efficacy of testosterone-estradiol implants in male rhesus monkeys

Rhesus monkeys (Macaca mulatta) were treated with testosterone (100 micrograms/kg/day) plus estradiol (0.5 micrograms/kg/day) via subcutaneous polydimethylsiloxane (PDS, Silastic) implants. This treatment caused a striking reversible sterility. No pregnancies were observed in females bred to the steroid-treated males. In contrast, there was no difference in pregnancy rate of females bred to control and steroid-treated monkeys for 14 weeks, beginning 17 weeks after removal of the steroid-filled implants.