The migratory pathways of the cells that form the endocardium, dorsal aortae, and head vasculature in the mouse embryo.

In contrast to the view that the yolk sac and embryonic circulatory systems form by two separate processes, our results indicate that Tal1-positive cells from the yolk sac contribute to both vascular systems. It may be that initial Tal1 activation in these cells is through a common mechanism.