Abstract
Engle 1 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 Simpson 2 confirmed this and demonstrated that glands from cryptorchid rats have more than normal potency. Severinghaus 3 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 from 3 to 5 times as much, by weight, was required in the rat as in the mouse. Similar results have been seen following the administration of sheep pituitary extracts. 4
It was shown that the ovarian response following implantation of equal amounts of normal male and female pituitaries is approximately 50% greater in the case of the male. Pituitaries from castrate and cryptorchid males and spayed females were of equal potency, about 70% greater than normal male glands, in each instance. Pituitaries from females subjected to extreme partial castration were only slightly less potent than those from totally spayed animals. Glands from gonadectomized males and females receiving daily injections of estrin (25 to 100 R.U.) and from castrate and cryptorchid males bearing functional ovarian grafts were somewhat less potent than normal pituitaries.
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