Current status of research on hormonal contraception in the male.

As yet not 1 single systemic male contraceptive has been developed to the stage of serious clinical testing although attempts to develop a male contraceptive antecede similar efforts to develop a female contraceptive. The initial approach in the male focused upon interruption of spermatogenesis by chemical means. The work was hindered by the limited knowledge of male reproductive tract physiology and during the subsequent 30 years the development of a male contraceptive failed to advance beyond the confines of research laboratories. Available physiologic data suggest 4 approaches to curtailment of fertility in the male: interference with spermatogenesis; interference with the mechanisms responsible for sperm motility; interference with epididymal sperm maturation; and interference with the formation or activity of acrosomal enzymes. 2 major directions have been taken in research efforts toward development of a male contraceptive: development of chemical agents with a direct action on the seminiferous epithelium; and interference with spermatogenesis by normal hormonal means. Focus in this discussion is on these 2 major approaches. It was not until the 1970s that serious investigation of a hormonal approach to male contraception began. Data accumulated in the late 1960s and early 1970s demonstrated the pivotal role of testosterone in spermatogenesis and revealed that its effect requires intratesticular concentrations several times greater than concentrations in the blood. This data prompted some investigators to consider the possibility that testosterone alone might be utilized as a male contraceptive and these testosterone studies are reviewed.