Much is known about how the limb develops from a small bud at specific, distinct regions on either side of the embryo into an organized functional structure complete with tendons, muscles, cartilage elements, neuronal input, blood vessels, scales and feathers.

The developing chick limb has been used as a developmental model system for studying cell interactions and tissue morphogenesis for more than 50 years ( Tickle, 2000). I also review the role of the TGFβ superfamily signalling pathway in the development of the chick limb vasculature: in particular, how antagonizing TGFβ signalling in the developing chick limb has shed new light on the role vascular smooth muscle cells play in vessel calibre control and how this work has added to our understanding of TGFβ superfamily signal transduction. In this review I outline how blood vessels are formed and maintained and how the developing chick limb is vascularized. Thus understanding how the vasculature forms and is patterned in the developing limb may further our understanding of limb development. Moreover, a lot of evidence recently points to molecules involved in morphological development also controlling vascular development. The vasculature supplies oxygen, nutrients and signals to developing tissues, allowing them to develop and grow.

However, the mechanisms underlying the development and maintenance of the vasculature of the developing limb are far from being completely understood. We are beginning to understand the mechanisms and signalling pathways that control and regulate the outgrowth and formation of the limb bud into a differentiated identifiable limb by late embryogenesis. The developing vertebrate limb has fascinated developmental biologists and theoreticians for decades as a model system for investigating cell fate, cell signalling and tissue interactions.

522 calibre brooke way