Histochemical studies of delta5-3beta-, 20lapha- and 20beta-hydroxysteroid dehydrogenases and possible progestagen...

Hamster eggs at various developmental stages were studied histochemically fro the presence of delta5-3beta-hydroxysteroid dehydrogenase (HSD) (pregnenolone as the substrate and NAD as the cofactor), 20alpha-HSD (20alpha-hydroxypregn-4-en-3-one and NADP) and 20 beta-HSD (20beta-hydroxypregn-4-en-3-one and NAD). All three enzymes were absent from ovarian eggs but were demonstrated in unfertilized and fertilized eggs up to the blastocyst stage. The activities varied only slightly.