Bile acid biosynthesis during development: hydroxylation of C27-sterols in human fetal liver

Several hydroxylase activities in bile acid biosynthesis were assayed in subcellular fractions of human fetal liver. The livers were obtained at legal abortions performed between gestational weeks 14 and 24. Microsomal 12 alpha-hydroxylase and mitochondrial 12 alpha- and 26-hydroxylase activities were detected from week 14. The microsomal fraction also had capacity for 25-hydroxylation, whereas 7 alpha- and 26-hydroxylase activities were hardly detectable. The variation of the hydroxylase activities between different experiments can be explained by inactivation during the abortion or workup procedure. The results are discussed with respect to earlier studies of bile acid biosynthesis during development and adult life.