Steroid metabolism of fetal tissues. II. Conversion of androstenedione to estrone.

The conversion of androstenedione to estrone in various tissues of 13 human fetuses ranging from 9 to 40 weeks of gestation was measured by a double isotope method in vitro. The data revealed differences in aromatization between cerebrum and hypothalamus. For hypothalamic tissue the conversion rate ranged between 0.01 and 1.40 per cent and for cerebral tissue between 0.00 and 0.07 per cent. The highest rate of conversion was found in liver tissue. Adrenal, kidney, lung, thymus, heart, skin, and gut were also examined and the results are compared with data in the literature.