SECRETION RATES OF OESTROGENS INTO THE OVARIAN VENOUS BLOOD OF PREGNANT RATS

Abstract

Summary. The secretion rates of oestradiol-17β and oestrone into the ovarian venous blood of rats on the day of pro-oestrus and on nine different occasions in pregnancy have been measured by collection of blood samples and assay of extracts by the intravaginal, tetrazolium-reduction method in mice. Secretion rate of oestradiol-17β at pro-oestrus and 1 to 2 days before parturition was about 3 ng/ovary/hr but was much lower at other times in pregnancy. There was a significant rise in oestradiol-17β secretion rate from the 3rd to the 4th day post coitum (81 to 500 pg/ovary/hr). Secretion rates of oestrone were always less than 300 pg/ovary/hr and did not show marked rises at pro-oestrus and before parturition. The physiological significance of the changes in ovarian oestrogen secretion rate is discussed.