Histochemical studies of 5-3 -, 20 - and 20 -hydroxysteroid dehydrogenases and possible progestagen production in hamster eggs

Abstract

Summary. Hamster eggs at various developmental stages were studied histochemically for the presence of Δ⁵-3β-hydroxysteroid dehydrogenase (HSD) (pregnenolone as the substrate and NAD as the cofactor), 20α-HSD (20α-hydroxypregn-4-en-3-one and NADP) and 20β-HSD (20β-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.