beta ; - estradiol secretion in normal and hypophysecto - mized chick embryos

horbar; Ovaries from decapitated, sham-operated and intact 18-day-old chick embryos were cultured in Medium 199 for 6 h, and the amount of 17f3-estradiol released into the culture media was determined by radioimmunoassay. Ovaries from decapitated embryos secreted significantly lower amounts of 17f3-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, 176-cestradio! production was significantly different between the 3 groups of embryos, the ratio being highest in the decapitates. 178-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 17f3-estradiol secretion by the chick embryo ovary even near hatching time.