Changes in the Hypophyses of Castrate and Cryptorchid Guinea Pigs

Engle1 has shown that the anterior hypophysis of the castrate rat is more potent in gonad-stimulating hormone than that of the normal animal. Evans and Simpson2 confirmed this and demonstrated that glands from cryptorchid rats have more than normal potency. Severinghaus3 showed that the same holds for the castrate guinea pig.In the present experiments anterior lobes from normal and castrate (4 to 12 months) adult male and female, and experimental cryptorchid (6 to 14 months) guinea pigs were implanted intramuscularly into immature female rats and mice. In all, 235 animals were used as donors and 83 as hosts. The relative impotency of the guinea pig pituitary in gonadotropic hormone made it necessary to implant considerable amounts in the rat. The amount of guinea pig anterior lobe (fresh gland weight) required to induce a significant increase in the immature rodent ovary was found to be approximately 4 times that of rat pituitary. In the case of the five types of guinea pig pituitaries mentioned above fro...