Drop several seeds over the surface of the pot and cover with a thin layer of vermiculite, a substance that can hold air, water and nutrients.

VOA: special.2009.04.21

The way we did this was to coax embryonic stem cells first to develop into the surface layer.

我们是这么做的,先诱导胚胎干细胞,发育成外胚层。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

First is that the ear develops from the surface layer of the embryo.

耳朵是由,胚胎的外胚层发育来了。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选