Within animals, oxygen exchange occurs within vascular transport networks containing
potentially billions of microvessels that are distributed throughout the body. By comparison,
large blood vessels are theorized to minimize transport costs, leading to tree-like networks
that satisfy Murray's law. We know very little about the principles underlying the organization
of healthy micro-vascular networks. Indeed capillary networks must also perfuse tissues with
oxygen, and efficient perfusion may be incompatible with minimization of transport costs …