Geometry genetics and developmental patterning

The development of an organism from egg to embryo to adult has fascinated scientists for centuries.  Over the past several decades genetics has defined the molecular constituents of the pathways that pattern the embryo, but the explosion in the number of components makes a literal quantitative representation impossible.  However a model that describes developmental decisions in geometric terms is able to predict from very approximate data on partial penetrance aspects of vulva patterning in the worm, which is a textbook system for the interaction of two developmental pathways.  Other applications of phenomenological modeling to temperature compensation in circadian clocks and other systems will be noted.  Self organized spatial patterns in micropatterned colonies of embryonic stem cells will illustrate future challenges for developmental modeling.