[A male contraceptive injection can be available within 5 years]

After more than two decades of attempts to develop a safe male contraceptive, the goal now seems attainable. Spermatogenesis, which is dependent on endogenous testosterone production in the testes, may be controlled by such exogenous steroid hormones as testosterone, gestagens, or combinations of them. The recent development of gonadotrophin-releasing hormone (GnRH) antagonists has provided an added means of depressing testosterone production. Other targets for interference with male fertility are the germinal epithelium (e.g. using the cottonseed oil product, Gossypol, or Triptyrigeum Wilfordii extract), or the maturing sperm in the epididymis (using immunoactive substances).