Transfer of 239Pu to mouse fetoplacental tissues.

Cross-placental transfer of 239Pu from the mother to fetus was studied in C3H mice. The activity of 239Pu in the conceptus was measured 24 hrs after the intravenous injection of 239Pu citrate on days 10.5 to 16.5 of gestation. More 239Pu was transferred to the conceptus when the plutonium was administered in the later stages of gestation; 0.12% of the injected dose per conceptus on day 10.5 and 1.3% on day 16.5. In all the gestational stages examined, the yolk sac and decidua contained more than 89% of the total activity distributed in the conceptus. The concentration of 239Pu in the yolk sac was about two orders of magnitude greater than that in the fetus. The 239Pu concentration in the maternal liver decreased with the gestational stage. In the early gestational stages the concentration in the maternal liver was greater than that in the yolk sac; but, this relationship was reversed in the later stages.