DRG macrophages interact with the vasculature. (A) Representative immunostaining of neurons, SGCs, endothelial cells, and macrophages in naive DRGs. Scale bar, 40 and 10 μm (inset). (B) 3D confocal images of DRG whole mounts to visualize neurons, macrophages, and endothelial cells. Scale bar, 30 μm (left) and 80 μm (right). (C) 3D confocal images of iDISCO-cleared whole mounts of DRGs with attached SpN and DRs and ventral roots (VR) stained with Iba1 and CD31. Scale bar, 400 μm. (D) Confocal Z-stacks of boxed areas in C and quantifications of macrophage and vascular density performed in indicated regions. n = 10 (SpN), 10 (DRG), 11 (DR) mice. Tukey’s multiple comparisons test. ***P < 0.001; ns, not significant. Scale bar, 40 μm. (E) Morphology of perivascular macrophages as measured by their spareness (high value indicates spider-like shape) and elongation (high value indicates cigar-like shape). Data are mean values of individual macrophages from n = 10 (SpN), 10 (DRG), 11 (DR) mice. Tukey’s multiple comparisons test. **P < 0.01, ***P < 0.001; ns, not significant. Scale, bar 10 μm. (F) Experiment schematic of i.v tracer injections. Created with https://BioRender.com. (G and H) (G) Representative confocal images (scale bar, 100 μm) and (H) quantification of BSA-A647 (20 mg/kg) uptake in Iba1⁺ macrophages 1 h after i.v injection. n = 4 mice/group. The experiment was performed twice. Tukey’s multiple comparisons test. ***P < 0.001; ns, not significant. (I) Uptake of goat IgG-A488 (4 mg/kg) in Iba1⁺ macrophages 4 h after i.v injection. n = 4 mice/group. The experiment was performed twice. Tukey’s multiple comparisons test. **P < 0.01, ***P < 0.001; ns, not significant. (J) Uptake of 70 kD dextran-TMR (10 mg/kg) in Iba1⁺ macrophages 2 h 45 min after i.v injection. The experiment was performed twice. Tukey’s multiple comparisons test. **P < 0.01, ***P < 0.001; ns, not significant.