TODDLER DISCOVERED

Ever heard of gastrulation?  When an embryo first appears, its cells are all mixed up.  Then, however, a signal makes it form into layers called the ectoderm, mesoderm and endoderm.  These layers ensure the cells are in the right places to develop into the right bits.  However, the signal to make gastrulation occur has only recently been discovered by scientists.  They have given it as a name the Toddler.  Very appropriate.