So first it's cell determination followed by cell differentiation. And that's when we form that specialized type of cell. Now, a good analogy to this is the way that we choose our careers. So we know at the early stage of a person's life before they begin school, they have the potential to become any professional. So they can become a physician, they can become a nurse, they can become a police officer, a banker, a quantitative analyst. So basically at the early stages of our lives, we are totipotent.