Regulation of blood vessel sprouting

► Angiogenic sprouting of vessels occurs via specialization of endothelial 'tip' cells. ► Endothelial tip cells interpret environmental cues to direct vessel patterning. ► Each tissue bed has guidance cues to spatially regulate sprouting. ► Context-specific patterning cues yield stereotypical or 'free-form' vasculature. ► A tip cell fuses with its target, and the new vessel acquires a blood-bearing lumen.