“原肠”造句

细胞的这种向里推进标志着原肠胚形成的开始.
This pushing - in of cells marks the start of gastrulation.

外胚层囊胚的外层,在原肠胚形成之后生后外胚层组织.
The outer layer of a blastula that gives rise to the ectoderm after gastrulation.