Developmental homoplasy: convergence in cellular differentiation.

There is an accumulating body of evidence that highlights the fact that one can identify convergence in programmes of cellular differentiation. That is, that a particular differentiated cell/tissue type can be generated via non-identical paths. Convergence is also seen in evolution and here it is termed homoplasy, thus one could term convergence in cellular differentiation, developmental homoplasy. It is important to appreciate its existence as it can confound our understanding of cellular differentiation. In particular, it highlights the point that the analysis of cellular differentiation in one region of the body may not generate an understanding that is generally applicable. The existence of the phenomenon of developmental homoplasy may lie in the evolutionary history of developmental processes, which are assembled over phylogenetic time. Such convergence in cellular differentiation may also have significance for understanding disease state and disease repair.