?
I don’t know for sure, but would imagine they could relatively simply. The IVF procedure (In-Vitro Fertilization) is incredibly common these days. That’s where the doctors remove eggs from the woman, fertilize those eggs, wait until they have divided to contain between 5 and 10 cells, and then implant back into the woman (or into another woman). A related procedure is called ICSI (I don’t know what the acronym stands for). In that procedure they actually choose one healthy sperm (they actually have a “beauty contest”, and try to pick the best one they can find), and inject that particular sperm directly into the egg. I would imagine that, because they are so easily able to manipulate the eggs and sperm to such a degree, they would be able to manually split the two cells of an embryo immediately after they first divide.