RESPONSES OF OVARIES OF IMMATURE CHICKENS TO AVIAN AND MAMMALIAN GONADOTROPHINS1

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Abstract
Transformation of follicles, from microscopic to macroscopic size including yolk formation could be induced by the administration of chicken pituitaries to intact or hypophysectomized prepuberal female chickens. In contrast, folli-cular development could not be caused by mammalian gonadotropin in either intact or hypophysectomized prepuberal or mature females. Exogenous mammalian gonadotropins did induce follicular development in females approaching sexual maturity. Gonadotropins of either source could act on the medullary portion of the ovary, causing an increase in ovarian weight and in comb growth. The refractory condition of the cortical portion of the immature chicken ovary is not due to morphological or physiological unreadiness to respond to gonadotropic hormones but is probably due to a qualitative inadequacy of the mammalian pituitary gonadotropic complex.