Direct imaging of capillaries reveals the mechanism of arteriovenous interlacing in the chick chorioallantoic membrane.

Understanding vascular development in vertebrates is an important scientific endeavor. Normal vasculatures generally start off as a disorganized capillary lattice which progressively matures into a well-organized vascular loop comprising a hierarchy of arteries and veins. One striking feature of vascular development is the interlacing of arteries and veins.