Palatogenesis and potential mechanisms for clefting.

This review concentrates on mechanisms of palatogenesis. This includes theories of shelf elevation, the role of matrix and identification of molecules and growth factors, which have key roles. The areas where failure to develop could potentially lead to clefting are highlighted. A key part of shelf fusion is the breakdown of the medial edge epithelium, a process that is probably dependent on enzymes involved in matrix turnover. There is good evidence that the matrix metalloproteinases may provide a common link to the multiple genetic and environmental factors that are known to cause clefting.