title: Endogenous origin of microbiologically-inactive cobalamins (cobalamin analogues) in the human fetus.
abstract: The cobalamin content of placenta, maternal and fetal sera was assayed by methods which measure microbiologically-active and microbiologically-inactive cobalamins. Only microbiologically-active cobalamins were present in the placenta but both types were present in both maternal and fetal circulations. We conclude that only microbiologically-active cobalamins cross the placenta and that the microbiologically inactive cobalamins in the fetus must arise by metabolism in situ.
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods; D005260:Female; D005312:Fetal Blood / Q000032:analysis*; D006801:Humans; D008297:Male; D010920:Placenta / Q000032:analysis*; D011247:Pregnancy; D014805:Vitamin B 12 / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014805:Vitamin B 12