The passage of thiamine across the rat placenta and its uptake by the fetal organs. II. The uptake of thiamine by fetal organs.

Having injected 3H-thiamine into the maternal bloodstream of rats in their 15th day of pregnancy, the uptake by the fetal organs (liver and cardiac muscle) of the 3H-thiamine which had been transported across the placenta was studied by electron microscope autoradiography and by measuring the radio-activity of the tissues, using the same methods reported in the first paper of this series. In the fetal liver both developed silver grains and radioactivity were found in greates amounts in specimens collected 5 hrs after injection. Developed silver grains were abundant in the mitochrondria, Golgi apparatus, rough-surfaced endoplasmic reticulum, glycogen area, and nucleus, indicating that these cell organelles take up thiamine and utilize it for the cell metabolism. In the fetal cardiac muscle, the developed silver grains and radioactivity were found in greatest amounts 2 hrs after injection. The silver grains were abundant in the glycogen area, Golgi apparatus, and myofibrils, but they were especially abundant in the mitochondria. This indicates that thiamine is taken up by these organelles and employed in the cell metabolism.