What happens to cells that fold inside the blastula during gastrulation in a triploblast? select the three that apply?

The series of cells moves in which the blastula-stage embryo folds inward, producing a differentiation of cells during gastrulation in a triploblast. They become endoderm, mesoderm and ectoderm. In addition, the most common features of gastrulation across triploblast is a change in the topological structure of the embryo from a simple to non-simple connected surface.