Histochemical distribution of delta5-3beta- and 17beta-hydroxysteroid dehydrogenases in hamster trophoblast

The histochemical distribution of delta5-3beta- and 17beta-hydroxysteroid dehydrogenases was demonstrated in hamster trophoblast between Days 8 and 15 of pregnancy. The delta5-3beta-hydroxysteroid dehydrogenase activity in the ectoplacental trophoblast of 8-day embryos was demonstrated by use of delta5-pregnenolone and dehydroepiandrosterone as substrates; between Days 11 and 15, activity was demonstrated in the trophoblastic giant cells of the placenta and in the intra-arterial trophoblast cells when delta5-pregnenolone was the substrate. Between Days 11 and 15, 17beta-hydroxysteroid activity was present in the spongiotrophoblast, labyrinth, placental giant cells and intra-arterial trophoblast cells, as shown by use of testosterone and oestradiol as substrates. Both enzymes were demonstrated in ectopic trophoblast cells, indicating that these activities are autonomous.