Metabolism of testosterone in previable human fetuses.

Labeled testosterone was injected into the umbilical vein of each of 4 male and 3 female previable fetuses at the time of laparotomy. After leaving the circulation intact for 3 min, the fetal tissues of each fetus were removed and the labeled metabolites present in each tissue were extracted, separated and isolated. Aliquots of tissue extracts were used for the qualitative analysis of metabolites following which metabolites were reisolated quantitatively from other tissue aliquots with the aid of the corresponding 3-H-labeled recovery markers. Testosterone and 11beta-hydroxyandrostenedione-4 were isolated from the adrenals and 5beta-androstanedione, androstenedione, etiocholanolone, androsterone, 5alpha-androstanediol, 5beta-androstanediol and testosterone were isolated from the livers. In addition, etiocholanolone and 5beta-androstanediol were isolated from the sulfate and glucuronide fractions of the livers. A sex difference in fetal testosterone metabolism was observed in the liver where the amounts of unconjugated 5beta-androstanediol in the male livers with no overlap in values. This conclusion has to be viewed with caution as only 4 males and 3 female fetuses were examined in these studies.