THE PATTERN OF OVARIAN SECRETION OF OESTRADIOL AND OESTRONE DURING PREGNANCY AND THE <i>POST-PARTUM</i> PERIOD IN THE HAMSTER

Abstract

Summary. A total of forty-nine samples of ovarian venous blood from pregnant hamsters was analysed by radioimmunoassay for oestradiol and oestrone. The secretion rate (ng/hr/ovary) and the concentration (ng/ml blood) of oestradiol were low on Day 1 of pregnancy, showed a significant rise before implantation on Day 3, and remained elevated on the day of implantation (Day 4) with no significant changes until after Day 9. Between Days 10 and 12, the values rose sharply to peak levels (P&amp;lt;0·01) which were followed by a significant (P&amp;lt;0·05) decline during the last 3 days of gestation. The secretion of oestrone paralleled that of oestradiol. The secretion of both oestrogens was very low during the post-partum period.