Where to put head and tail?

Formation of the body axes is a critical part of embryonic development. They guarantee that all body parts end up where they belong and that no ears grow on our backs. The head-tail axis, for example, determines the orientation of the two ends of the body. It was previously assumed that this axis is largely determined by the interplay between the Nodal and BMP signals. However, there appears to be another player in this system, as researchers have now discovered by using an embryo-like model system they developed. In the absence of BMP, the signalling molecule beta-catenin takes on the role of the Nodal antagonist. This new mechanism could be a flexible solution for axis formation in embryos with different shapes.