Exovagination of Newt Endoderm: Cell Affinities Altered by the Mesodermal Inducing Factor.

Implantation of a highly purified mesodermal inducing factor in the blastocoel of early gastrulae results in the spreading of endoderm over the ectoderm. The effect can be explained by a change in cell affinities in the ectoderm, initiated by the mesodermal factor.