gastrulation

noun Embryology.

1. the formation of a gastrula.
2. any process, as invagination, by which a blastula or other form of embryo is converted into a gastrula.

noun

1. embryol the process in which a gastrula is formed from a blastula by the inward migration of cells

n.

1. Transformation of the blastula into the gastrula.