Steroidogenesis by ovaries and testes of the European catfish, the wels (Silurus glanis), in vitro.

Testosterone, 3α,17-dihydroxy-5β-pregnen-20-one, 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) and 5β-pregnane-3α,17,20β-triol were identified as the major metabolites of [(3)H] 17-hydroxyprogesterone in ovarian incubations of the European catfish Silurus glanis. 17,20βP and the reduced triol were present only in ovaries from fish primed with carp hypophysial homogenate (chh) while testosterone yields were significantly higher in controls than in treated fish. 11-Ketotestosterone, 11β-hydroxytestosterone and 17,20α-dihydroxy-4-pregnen-3-one (17,20αP) were identified as the major metabolites of [(3)H]17-hydroxyprogesterone in in vitro incubations of testes of a spermiating catfish. There was no significant production of conjugates or other water soluble metabolites by either sex. The stimulation of plasma 17,20αP, 17,20βP and 11β-hydroxytestosterone by chh in primed but not control males suggests that the role of these steroids in spermiation should be further examined.