Still Stems But not much longer. These three photos show early cell duplication and division, with each new cell exactly like the others, with all the genetic instructions to make a whole person, or any cell of a person’s body. A technician could remove one cell and test it for defects, and the remaining cells would still grow into a fetus as if nothing had happened. But in another 24 hours, that is impossible–the stem cells would begin to differentiate and any removal might be lethal.