BIOSYNTHESIS OF ESTROGENS IN IN VITRO PERFUSION OF THE HUMAN PLACENTA

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Abstract
Perfusions of the human term placenta with radioactive androstenedione, testosterone, DHEA, progesterone, cholesterol and estradiol-17β as precursors were carried out and the formation of estrogens was investigated. After perfusion for three hours with human whole blood, added with human chorionic gonadotropin and cofactors, radioactive metabolites in the perfusate were studied. The radioactive metabolites were purified by chromatography at each step of purification. Estrogens were measured by the Kober reaction, and the radioactivity was counted by the gas flow counter. These experiments demonstrated that C-19 steroids were aromatized in a high yield by the perfused human placenta to estrone and estradiol-17β in the ratio of approximately 3 to 1, but that it was not capable of converting androgens to estriol. It was also noted that there was no conversion of estradiol-17β to estriol. In the perfusion study with DHEA, which is considered to be an important intermediate to estriol in the feto-placental unit during pregnancy, 10.7% of the initial radioactivity was recovered as a polar phenolic compound which behaved like 16-epiestriol on preliminary identification. Furthermore, neither progesterone nor cholesterol converted to estrogens in the human perfused placenta.