Mouse submandibular gland morphogenesis: A paradigm for embryonic signal processing

Signal processing is the sine qua MOM Of embryogenesis. At its core, any si ngle signal transduction pathway may be understood as classic Information T heory, adapted as an open system such that, because of networking, the "rec eiver" is presented with more information than was initially signaled by th e "source". Over 40 years ago, Waddington presented his "Epigenetic Landsca pe" as a metaphor for the hierarchical nature of embryrogenesis. Mathematic ally, Waddington's landscape may be modeled as a neural net. The "black box " of the neural net is an interacting network of signal transduction pathwa ys (using hormones, growth factors, cytokines, neurotransmitters, and other s) which inform the Boolean logic gates. An emerging theme in developmental biology is that defined sets of epigenetic circuits are used in multiple p laces, at multiple times, for similar and sometimes different purposes duri ng organogenesis. As we shaw here, submandibular gland embryonic and fetal development is a splendid paradigm of these epigenetic circuits and their p henotypic outcomes, such as branching and lumen formation.