Abstract
SUMMARY: Immature male rats were (1) exposed to X-rays, or (2) made cryptorchid, or (3) subjected to a combination of the two and placed in parabiosis with castrated males. Pairs were autopsied at various intervals up to 46 weeks and effects upon gonads and accessory sex organs evaluated. Androgen production in response to endogenous gonadotrophins from a castrated animal is greater in irradiated than cryptorchid testes. The stresses imposed upon irradiated, intra-abdominal testes greatly reduces their capacity to produce androgen in response to gonadotrophins.