Effect of Gonadotropins and LH‐RH on Functional Differentiation of Immature Monkey Testis

Response of the immature monkey testis to gonadotropins and LH‐RH has been assessed by measuring plasma and testicular testosterone concentrations. Administration of 50 μg of LH or FSH for 5 days to immature animals, did not significantly increase the plasma or testicular testosterone levels. When a daily dose of 200 μg of LH or 150 IU hCG was given, there was a marked increase in testosterone levels in the plasma and the testicular tissue. In vitro experiments indicate that whereas the testicular tissue of normal and FSH‐primed monkeys is refractory to gonadotropins, the testicular tissue of monkeys sensitized with LH shows enhanced androgenesis when incubated with LH. Unlike the adult, the plasma testosterone levels did not increase following an intravenous injection of 2 μg of LH‐RH. This amount of LH‐RH, however, produced a measurable increase in plasma testosterone in gonadotropin‐primed immature monkeys.