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A Reversal in the Ratio of Estrone and Estradiol during Late Pregnancy in the Uterine Vein of Ovariectomized Rhesus Monkeys^*

D. J. DIERSCHKE, W. B. WEHRENBERG, R. C. WOLF, J. R. CLARK and J. A. ROBINSON

Wisconsin Regional Primate Research Center, Department of Meat and Animal Science and Department of Physiology, University of Wisconsin Madison, Wisconsin 53706

Address all correspondence and requests for reprints to: Dr. Donald J. Dierschke, Wisconsin Regional Primate Research Center, 1223 Capitol Court, Madison, Wisconsin 53706.

Abstract

To evaluate hormone secretion by the fetoplacental unit in the absence of ovaries, eight rhesus monkeys were ovariectomized on days 22 or 48–50 after mating and blood samples were obtained from the uterine and femoral veins during the remainder of pregnancy. Estradiol declined significantly (P < 0.05) in uterine vein samples from about day 100, becoming equivalent to that in the peripheral circulation near the time of delivery. During the same interval, uterine vein estrone increased significantly (P < 0.01) and reached the highest concentrations at delivery. Changes in the peripheral concentrations of these two steroids were smaller but followed a similar pattern. Progesterone in these samples varied in an apparent random manner. After delivery, all three steroids declined to low levels. Serum concentrations of CG were undetectable in all uterine vein samples taken after day 37 of pregnancy. These observations indicate that estrogen production by the fetoplacental unit undergoes a distinct adjustment in favoF of estrone'during the terminal stages of pregnancy, an adjustment which may involve fetoplacental maturation and which may be preparatory to the initiation of parturition.

Footnotes

^* This research was supported by Grants RR-00167, MH-21312, and HD-06736 from the NIH and by Ford Foundation Grant 630–0505A. Publication no. 17–046 of the Wisconsin Regional Primate Research Center.

Trainee of the Endocrinology-Reproductive Physiology Training Program.

Postdoctoral Research Fellow of the NICHHD (HD-01816), USPHS. Present address: Animal Science Department, Texas Tech University, Lubbock, Texas.

Received August 12, 1977.