The very top of the wire drawing represents the only part of the ocean landscape that can be seen on the surface of the water: It is Bouvet Island, one of the most isolated islands in the world.

VOA: special.2009.05.06

It's these cells that are sitting at the surface here that are responsible for determining what becomes part of us and what stays outside.

位于肠道表面的细胞,决定了,吸收哪些分子而排出哪些分子

耶鲁公开课 - 生物医学工程探索课程节选