柯林斯詞典gastrula /?ɡ?str?l?/ 1. N a saclike animal embryo consisting of three layers of cells (ectoderm, mesoderm, and endoderm) surrounding a central cavity (archenteron) with a small opening (blastopore) to the exterior 原腸胚→see also ectoderm , mesoderm , endoderm 返回 gastrula