"gastrula"^^ . "01462544-n"^^ . . . . "0"^^ . "101462544"^^ . . "101385899"@en-us . . "gastrula"@en-us . "0"^^ . . . . . "double-walled stage of the embryo resulting from invagination of the blastula; the outer layer of cells is the ectoderm and the inner layer differentiates into the mesoderm and endoderm"@en-us .