复数： blastulas

The process in which a gastrula develops from a blastula by the inward migration of cells .

由于细胞向内移动囊胚形成胚囊或肠胚的过程。

Embryonic stem cells are cells extracted from the blastula , the very early embryo , that have an exceptional ability to duplicate in vitro , that is in a test tube , and to become cells of almost any tissue .

胚胎干细胞是从最早的胚胎囊胚中提取出来的，它具有超强的体外繁殖（也就是在试管中繁殖）能力，且可以变成几乎任何一种组织细胞。