So if you think of a shell, you can actually just think of an egg shell, that's probably the easiest way to think of it, where the yolk, if you really maybe make it a lot smaller might be the nucleus.

可以把它想成，个蛋壳，这也许是，最简单的思考办法,蛋黄如果，缩小非常多倍的话,就可以想象成核子。

麻省理工公开课 - 化学原理课程节选

And that certainly wasn't true way back at the start of A, as the fertilized egg first begins to split and multiply, subdivide and make organs.

显然不是在A阶段这么早就开始的，当受精的卵子开始分裂繁殖，继续分裂，形成器官。

耶鲁公开课 - 死亡课程节选