translation.en: Because in essence what it means is you can take a cell, which is a pluripotent stem cell, which is like a skier at the top of a mountain, and those two skiers become two pluripotent stem cells, four, eight, 16, and then it gets so crowded after 16 divisions that those cells have to differentiate.
translation.zh: 因为从本质上说 这就意味着我们可以取一个 多能干细胞 好比山顶上的滑雪者 两个滑雪者就是两个多能干细胞 分裂成4个，8个，16个 然后变得越来越拥挤 16次分裂之后 这些细胞不得不进行分化