A Conversation with Maria-Elena Torres-Padilla.

Dr. Torres-Padilla: We are interested in understanding how these very early cells of the very early embryo are actually able to establish andmaintain the largest plasticity that one can think of. It’s quite remarkable. Everybody, at some point, was a single cell. The question is how that single cell is able to generate a new being: not only all the tissues and cells that we have in our body, but really how that single cell builds up the whole program that we call “totipotency.” The system is difficult in that we have very limited materials. Obviously, we don’t do experiments with humans, but we do use the mouse and other species as a model to understand these transitions. But you don’t get a lot of embryos to try to understand biochemically what happens with stem cells and so on. The system is really fascinating, but it is a challenge.