It's this - its cells in this region here, this inner cell mass that that's the source of embryonic stem cells, cells from inner cell mass here.

就是这个,在这片区域的胚胎细胞,即内细胞群,而胚胎干细胞的来源所在,就是源自这里的内细胞群

耶鲁公开课 - 生物医学工程探索课程节选