An Anglo-French research team has created a chicken with teeth, shedding new light on the signaling mechanisms that underlie cell differentiation in organ development. Chicken embryos were implanted with murine cells that constitute teeth and parts of the head, which resulted in the development of tooth-like structures not found in any bird. According to Paul Sharpe, professor of craniofacial development at King's College London, whose team collaborated with French researchers in Marseilles and Nantes, the murine cells recognized signals instructing them to form teeth. "Something has happened during evolution such that birds can no longer respond to those signals and form a tooth," says Sharpe.
It is clear, Sharpe adds, that birds have lost some of the fundamental genes needed to form unique teeth proteins, because the chickens' teeth were only partially formed. But, as Sharpe points out, the experiments highlight the fact that in the embryo, the same genetic ...
