Microcirculatory flow changes during tissue growth

Red blood cell (RBC) velocities, lumen diameters, and volumetric flow rates were determined as functions of position and time in the microvessels of repairing tissue grown in a transparent rabbit ear chamber. By making repeated measurements in the same region, and in many instances, in exactly the same vessel over the entire growth period, we have discerned a distinct microcirculatory flow trend. The flow to a particular region (vessel) increases rapidly after an initial lag time, peaks out, and eventually decays to a steady-state level. This behavior is analogous to the vessel density pattern previously observed in this laboratory, but is delayed in time 1 to 2 weeks. These observations are consistent with mechanical, biochemical, and physiological mechanisms underlying neovascularization, tissue growth, and blood flow regulation, and provide a quantitative understanding of these processes.