THE MEASUREMENT OF PLACENTAL PERMEABILITY WITH RADIOACTIVE SODIUM

Abstract

Placental permeability in the rat was measured with radioactive Na. During the last 4 days of pregnancy there is a high inverse correlation between fetal mass and the placental transmission of radioactive Na per unit wt. of fetus, i.e., fetal wt. in the rat appears to be detd. by genetic forces alone. The total amt. of radioactive Na transmitted to a fetus is independent of fetal size.