During most instances of angiogenesis, not only are the capillaries or terminal vessels generated and modified, but the supplying vascular system is subjected to remodeling as well. Intussusception, i.e., transluminal pillar formation, is one essential mechanism for growth, arborization, bifurcation remodeling, and pruning. Complex and efficient vascular beds can thus be generated by local interactions between vascular cells and hemodynamic conditions.