| pubmed-article:4041374 | pubmed:abstractText | 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. | lld:pubmed |
