Abstract
With the aim of studying the biosynthesis and the biological activity of estrogen, particularly of estriol, in the placenta, and besides obtaining some informations on the metabolism of estrogen in the fetus, the present author conducted some experiments. The results obtained were in summary as follows;
1. The placenta contains estriol in a higher concentration than estrone and estradiol-17β.
2. Estriol in urine and blood increases remarkably during pregnancy but decreased to nearly normal value in 72 hrs. after labor.
3. Estriol was found in higher concentration in the cord blood than in the maternal blood.
4. No difference in partitive concentration of estrogens was found in arterial and venous cord blood.
5. Estrone, estradiol-17β and estriol were all in high concentration in meconium and amniotic fluid.
6. In the placenta, estrone was found elaborated from cholesterol, progesterone and testosterone, but no conversion from sodium acetate to estrone could be proved.
7. Interconversion of estrone to estradiol-17β and vice versa could be observed in the placenta but no effect of gonadotrophin was apparent in accelerating interconversion of estrone and estradiol-17β, except that pregnant mare serum gonadotrophin showed a slight effect on conversion from estradiol-17β into strone.
8. When incubated in serum of pregnant women, however, conversion in the placenta from estrone to estradiol-17β was much more active than in Krebs-Ringer solution, and here conversion from estrone to estriol was also observed.
9. Estriol was weaker in catabolic activity than estrone and estradiol-17β.
10. Estriol acted depressant upon the oxygen consumption of the interbrain.
11. Estriol in large doses acted upon the uterine muscles, reduced the pressure in the cervical canal sometimes to zero and heightened the tonus of the vaginal wall.
