Development of Activity of 3β-Hydroxysteroid Dehydrogenase in Human Fetal Tissues and in Two Anencephalic Newborns

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Abstract
The histo-chemical distribution of activities of 3[beta]-hydroxysteroid dehydrogenase (3[beta]-HSD) with DHA[Dehydroepiandrosterone] and DHAS [Dehydro-epiandrosterone sulfate] as substrates, and of 17[beta]-hydroxysteroiddehy-drogenase (7[beta]-HSD) with testosterone and estradiol-17[beta] as substrates, has been studied in the steroidogenic endocrine tissues and the liver of several normal human fetuses, and of 2 anencephalic infants. Activity of 3[beta]-HSD first appears in testicular Leydig cells during the second month of gestation, rises rapidly to a maximum at the time or urethral fold closure during the third month, and decreases to the end of gestation. Activity of this enzyme next appears about the beginning of the 4 month, both in the adrenal neocortex in both sexes, and in ovarian follicular cells, and rises rapidly to a maximum during the period of urethrovaginal differentiation. Activity of this enzyme is minimal to absent in the adrenal fetal zone throughout gestation. In hepatic cells, staining by this enzymatic activity increases roughly in proportion to fetal age, while in the placental trophoblast it is strong throughout the latter two thirds of gestation. Staining by this enzymatic activity occurs in the adrenal neocortex, the liver and gonads of both a male and a female anencephalic newborn, but is absent in the very small amounts of fetal adrenal zone present. With DHAS as substrate, activity of 3[beta]-HSD is demonstrable only in placental trophoblast and not in any other of the tissues tested. Staining by activity of 17[beta]-HSD occurs only in hepatic and placental stromal cells. This study has shown that there is a difference between the sexes in the time of appearance of the activity of 3[beta]-HSD during fetal development, which may be temporally correlated with the abnormal development of the external genitalia in the 2 sexes with congenital deficiency in activity of this enzyme.