Doctor, can you tell me exactly how stem cells work? Well you ...
Cartman: Doctor, can you tell me exactly how stem cells work?
Doctor: Well you have trillions of cells in your body, heart cells, skin cells, brain cells and so on. But before a cell is designated as a toenail cell, or a pancreas cell, it's what we call a stem cell. Sort of like a blank cell, do you understand?
Cartman: Not at all, but go on.