the mechanism of cell commitment in early embryos differs between mice and cows, suggesting that development in mice may not be representative of development in other mammals, including humans. This research suggests "that the mouse alone is not the ideal model if you want to study mammalian embryogenesis," said Michael Bader, a cardiovascular biologist who works on rat embryogenesis at the Max Delbruck Center for Molecular Medicine in Berlin and was not involved in the research.