Embryology of the upper limb: the molecular orchestration of morphogenesis.

Accumulating data on the molecular interactions that occur during limb development have greatly enhanced our understanding of the process of limb morphogenesis. In this chapter, the key morphologic events are described, the broad categories of molecules involved are defined, the known molecular cascades and specific pathways that orchestrate limb development are reviewed. In addition, cascades disrupted by known genetic mutations associated with limb malformations are identified.