THE TRANSFER OF RADIOACTIVE SODIUM ACROSS THE PLACENTA OF THE GOAT

Abstract

The rates of placental transfer per unit wt. of placenta were measured with Na24 from a gestation age of about 9 wks. until term in the goat. There is a 3 or 4-fold increase in transfer rate from the 9th wk. to about the 19th and 20th wks. of pregnancy. The relative growth curve of the goat fetus is similar to the curve of rate of transfer of Na24 to a unit wt. of fetus at different periods of pregnancy. The placenta of the goat belongs to the syndesmochorial group. Its rate of transfer of Na24 per g. of placenta is of the same order of magnitude as that of the endotheliochorial placenta of the cat at comparable stages of pregnancy.