This pushing-in of cells marks the start of gastrulation . 细胞的这种向里推进标志着原肠胚形成的开始。
2.
Asymmetrical distribution of cortactin appeared when gastrulation starts , with higher staining in the dorsal part of the embryo , while much lower in the ventral part 在胚盾附近区域，即未来的胚胎背侧，染色信号较强，皮层蛋白标志了正在发生汇聚迁移的细胞。
