17 beta-estradiol secretion in normal and hypophysectomized chick embryos.

Ovaries from decapitated, sham-operated and intact 18-day-old chick embryos were cultured in Medium 199 for 6 h, and the amount of 17 beta-estradiol released into the culture media was determined by radioimmunoassay. Ovaries from decapitated embryos secreted significantly lower amounts of 17 beta-estradiol than those from intact embryos, but there was no difference when they were compared to ovaries from sham-operated embryos in this respect. On an ovarian weight basis, 17 beta-oestradiol production was significantly different between the 3 groups of embryos, the ratio being highest in the decapitates. 17 beta-Estradiol concentration was the same in serum from both decapitated and intact female embryos. Considering these results, it is concluded that the hypophysis does not control 17 beta-estradiol secretion by the chick embryo ovary even near hatching time.