HISTOCHEMICAL DISTRIBUTION OF 3β-HYDROXYSTEROID DEHYDROGENASE AND 17α- AND 17β-HYDROXYSTEROID DEHYDROGENASES IN THE PLACENTA AND FOETAL MEMBRANES OF THE RAT

SUMMARY The placenta and the foetal membranes of rats (pregnant 5–21 days) have been assayed by histochemical methods for 3β-hydroxysteroid dehydrogenase (3β-HSDH), NAD-dependent, and 17α- and 17β-hydroxysteroid dehydrogenases (17α- and 17β-HSDH), both NAD and NADP-dependent. 3β-HSDH was limited to the trophoblastic giant cells of the first generation, whereas 17α- and 17β-HSDH were present in both the first- and second-generation giant cells and also in the endodermal cells of the inverted yolk sac placenta.