An extensive increase of junctional communication capacity in endoderm development of the Xenopus embryo

The present result shows that in blastula and gastrula stages although endoderm cells of the Xenopus embryo may be electrically coupled with each other, most of them can not detectably transfer the 376 dalton molecular weight tracer, the carboxyfluorescein, to their contiguous neighbor cells. They become capable of such junctional dye transfer at the end of gastrulation. This transition reflects temporally well ordered development of junctional communication capacity from low to high level, which may be related to the developmental program of endodermal cellular differentiation. The time course of this transition provides a measure for study of the effects of various factors on the development of junctional communication capacity in this embryo.