Xenopus cadherin 5 is specifically expressed in endothelial cells of the developing vascular system

Vasculogenesis is an important, multistep process leading to the formation of a functional primary network of blood vessels in the developing embryo. A series of interactions between secreted growth factors and their specific receptors leads to the specification of mesodermal cells to become hemangioblasts, which then differentiate into angioblasts. These subsequently proliferate, coalesce into cords and finally form tubular vascular structures. For proper function of these primary blood vessels, the close connection of endothelial cells is required. This is conferred by the interaction of an endothelium specific cadherin (Cadherin-5), starting during early vascular development. However, this interaction remains important throughout life and ageing. Therefore, cadherin-5 is a useful marker for late stages of vasculogenesis in several vertebrate species. To establish cadherin-5 as a marker for vascular studies in Xenopus, we cloned the Xenopus laevis ortholog and analyzed its expression pattern during embryogenesis.