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
例句
用作名词(n.)
The resulting gastrula consists of an outer ectoderm, an inner endoderm, and a mesoderm layer positioned between them.最终原肠胚由一个外肠胚，内肠胚，和一个中肠胚构成。
