Hypophysis and estradiol secretion in the chick embryo

Ovaries from 10- to 18-day-old chick embryos hypophysectomized by partial decapitation were cultured in vitro and their estradiol secretion was compared to that of ovaries from control embryos. The production of estradiol was not less in the decapitated than in the control embryos at 15-18 days, neither per ovary nor on the basis of ovarian weight. However, the difference was significant at 10-11 days. These results suggest that the hypophysis controls estradiol secretion by the chick embryo ovary in the early stages, but not in the later ones.