Incorporation of Tritiated Uridine into Amphibian Eggs

Abstract

THE incorporation of labelled precursors into amphibian embryos is limited by the presence of a coat which covers the embryo and which renders the embryo impermeable to a large number of substances. One of them is uridine. However, we found that embryonic cells the coat of which has been disintegrated by placing them in a medium totally devoided of calcium incorporate tritiated uridine very rapidly, while the control embryos do not. Using this procedure, we have been able to follow the incorporation of this substance into dissociated embryonic cells at different stages of development.