Fig. 1. Image explaining the contraceptive effect of exogenous testosterone. In summary, it works by 2 mechanisms, decreasing intra-testicular testosterone, and inhibiting spermatogenesis. Most of the intra-testicular testosterone is made by the Leydig Cells in the testis. When exogenous testosterone is present, it inhibits gonadotropin-releasing hormone (GnRH) production which in turn inhibits luteinizing hormone (LH) production and decreases endogenous testosterone production by the Leydig cells, decreasing the intra-testicular testosterone concentration. Inhibiting GnRH production also inhibits follicle stimulating hormone (FSH) release, which impairs spermatogenesis in the Sertoli cells. Fig. 1. Image explaining the contraceptive effect of exogenous testosterone. In summary, it works by 2 mechanisms, decreasing intra-testicular testosterone, and inhibiting spermatogenesis. Most of the intra-testicular testosterone is made by the Leydig Cells in the testis. When… World J Mens Health. 2019 Jan;37(1):45-54. https://doi.org/10.5534/wjmh.180036