Mammalian embryonic development is an extremely complex and precise process. Specific molecular events act as cues that tell cells in the embryo where to move and what type to mature into. The expression levels of different genes in these cells can change at certain points of development, helping produce the signals that further the progression. Now, researchers at Tokyo Medical and Dental University (TMDU) have used experiments with mice to show how a particular gene helps direct generation of tissues in the head.