Gases and nutrients move back and forth between the decidua basalis and the fetal veins, by diffusing through the tissue layer of the thin chorionic villi.

气体和营养物质通过在薄绒膜绒毛组织层之间扩散，在基蜕膜和胎儿静脉之间来回移动。

Check it out: the dermal tissue layer is the perfectly neat row of cells all around the edges — it's giving the stem a tight hug.

真皮组织层是一排完全整齐的细胞围绕着边缘——它给了茎一个紧紧的拥抱。

It's filled with a jelly, which is called the vitreous, and then the tissue layers of the eye are really really thin, almost like this thin outer layer of the grape.

它充满了胶状物，叫做玻璃体，然后眼睛的组织层非常非常薄，几乎就像葡萄薄薄的外层。