Whether human or animal, vertebrate or invertebrate, nearly every creature begins life as a tiny clump of cells. Before those cells can begin blossoming toward being a fully formed organism, however, they first must reorganize themselves into layers, each of which goes on to form complex structures such as internal organs, skin, muscle, and bone.
The signals that trigger that reorganization, however, have been largely a mystery, until now.
Scientists at Harvard have identified a previously unknown embryonic signal, dubbed Toddler, that instructs cells to move and reorganize, through a process known as gastrulation, into three layers: the ectoderm, mesoderm, and endoderm. The new signal is described in a Jan. 9 paper in the journal Science.