Placental transfer and fetal distribution of 3H-retinoic acid in rats.

The placental transfer of 3H-retinoic acid in vitamin A deprived and vitamin A supplemented pregnant female rats was studied on 20th day of gestation and compared with 3H-retinyl acetate. Radiolabelled compounds were administered to pregnant mothers orally in groundnut oil six hours before sacrifice. The distribution of radioactivity of the two compounds was studied in maternal intestine, liver and plasma and fetal brain, heart liver lung and placenta. The transfer of 3H-retinoic acid across placenta was restricted as compared to that of 3H-retinyl acetate which may explain the reason why retinoic acid does not support fetal growth.