Pattern Formation in Vertebrate Limbs

Patterns are an essential element of all life forms. The concepts of pattern formation are positional information, a mechanism for conductance of the positional information, and an interpretation system . The developmental patterns of the embryonic chick demonstrate two types of patterns. The shape of a bone demonstrates patterns as forms. The processes of development are illustrations of dynamic patterns. In the embryonic chick limb bud, the apical ectodermal ridge exhibits a pattern of required presence for development of the musculature, cartilage elements, vascular system and expression of the homeobox genes. The two current models of pattern formation are the zone of polarizing activityprogress zone model, and the polar coordinate model are reviewed. A new pattern formation model is proposed. The information and memory model is founded on the premise that cells have a working memory which is cumulative, accessible, and passes intact from one cell to its progeny.