Fig. 9: Blood flow stalls and regression in capillaries neighboring dilation.

a A divergent bifurcation close to the arteriole-capillary transition zone. One branch of the bifurcation is dilated from pericyte loss 3 days post-ablation, and the resulting re-direction of flow creates a stall in the alternate, covered branch. Images are representative examples from 14 ablation experiments across adult and aged mice. I.v. dye = intravenous dye. b Example of blood flow defects at a capillary junction near the arteriole-capillary transition zone. At 21 days post-ablation, a central capillary is uncovered, dilated, and flowing. The other branches have stalled in flow or regressed. c Occurrence of stalls in triple off-target sham irradiation and triple pericyte ablation experiments. Unpaired t test with Welch’s correction for unequal variances (two-sided), t(16.10) = 2.698; overall effect *p = 0.0158, for n = 6 off-target irradiation experiments (3 in adult mice, 3 in aged mice), n = 14 pericyte ablation experiments (7 in adult mice, 7 in aged mice). Data are shown as mean ± SD. d Additional example of a capillary regression occurring after a prolonged stall. e Plot of the relative location of stall and regression events following pericyte ablation, by branch order from a dilated segment. Observations from n = 14 ablation experiments (7 in adult mice, 7 in aged mice). f Schematic summarizing findings of blood flow interruption following pericyte coverage loss.