Transfer of 144Ce to Mouse Embryos and Offspring Via Placenta and Lactation

Abstract

Female albino mice were injected intramuscularly with 144Ce-citrate, and mated at different periods. Their litters were whole body counted immediately after delivery and thereafter for another 60 days, and the results compared to the body burden of their mothers. Some fetuses were extracted by Caesarian intervention 24 hr before expected delivery and whole body counted. The distribution of 144Ce in various organs of the adult female mice, as well as of some suckling young mice, was also studied, as a function of time. The passage of 144Ce through the placenta when the isotope is readily available in the circulation was clearly demonstrated. In cases where there were long intervals between the administration of the isotope and delivery, placental transfer was also evident, but further investigation would be desirable. There was a clear increase in radioactivity in the litters during the suckling period even in those delivered several months after the contamination of the mother, when the Ce is already concentrated mainly in the mother's skeleton. Absorption of cerium from the gastrointestinal tract was found to be about 1.5% of the total intake during the suckling period. This, if confirmed, would suggest that the discriminatory ability of the gastrointestinal tract is not as efficient in mice during the early period of life, as in the adult stage.