Did They Kill a Mouse?

They were allowed to develop for over eight days, which is almost half of the mouse jestation period. By which point they had formed all the early progenitors of organs. That includes a beating heart, blood stem cell circulation and well shaped brain. The shape of internal structures and the gen expression patterns of these synthetic embryos matched natural ones to within 95%. Soa they were, they were growing 95 % mice. But what was the other five percent? And how would that manifest itself when they were released into the world? We'll never know.