Metabolism of progesterone by chorionic cells of the early sheep conceptus in vitro.

Progesterone-4-14C was extensively metabolized during incubation with dispersed trophoblast prepared from chorionic membranes of the 21-day sheep conceptus. Of the metabolites formed, 17, 20 alpha-dihydroxypregn-4-en-3-one, 20 alpha-hydroxypregn-4-en-3-one, 20 beta-hydroxypregn-4-en-3-one, 5 alpha-pregnane-3 alpha, 17,20 alpha-triol, 5 beta-pregnane-3 alpha, 17,20 alpha-triol, 5 beta-pregnane-3 alpha,20 alpha-diol, 3 beta-hydroxy-5 alpha-pregnan-20-one, 3 alpha-hydroxy-5 beta-pregnan-20-one, 20 beta-hydroxy-5 beta-pregnan-3-one, 5 alpha-pregnane-3,20-dione and 5 beta-pregnane-3,20-dione were identified. These findings indicate that the sheep conceptus acquires extensive steroid metabolizing capability very early in pregnancy.