3β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN THE HUMAN FOETAL TESTIS

Abstract

ABSTRACT Sections of testes from nine human foetuses ranging in crown-rump length from 3.0 to 18.3 cm were incubated to determine 3β-hydroxy-steroid dehydrogenase activity histochemically with the following steroids: 3β-hydroxy-pregn-5-en-20-one (pregnenolong). 3β,17α-dihydroxy-pregn-5-en-20-one (17α-hydroxypregnenolone). 3β-hydroxy-androst-5-en-17-one (DHA). 3β,17β-dihydroxy-androst-5-ene (androstenediol). 3β-sulphoxy-pregn-5-en-20-one (pregnenolone sulphate). 3β-sulphoxy-1 7α-hydroxy-pregn-5-en-20-one (17α-hydroxy-pregnenolone sulphate) 3β-sulphoxy-androst-5-en-17-one (DHAsulphate). 3β-hydroxy-5α-androstan-17-one (epiandrosterone). Pregnenolone and DHA gave a colour reaction in the interstitium of all testes studied. 17α-hydroxypregnenolone was utilised by testes from foetuses of C-R length 8.8 cm and over, androstenediol by testes from foetuses of C-R length 6.1 cm and over. These facts are thought to support the concept of separate substrate-specific 3β-hydroxysteroid dehydrogenases in the testis. Pregnenolone sulphate was used by the interstitial cells of all testes studied but gave a stronger reaction than the free steroid. 17α-hydroxy-pregnenolone sulphate was used by all foetal testes surveyed. DHA sulphate was not well used by the interstitial cells. The utilisation of steroid sulphates in a different manner from the free steroids in this histochemical system may mean that the presence of a sulphate group affects enzyme-substrate binding or that a steroid sulphatase is involved. Intense formazan deposition followed incubation with epiandrosterone in all testes studied. This seems to imply that a δ5 configuration is not necessary for enzyme-substrate binding.