Infiltrated cells are immunoreactive for macrophage markers. (A) The diagram represents a coronal section where the pictures in B–E were taken (red box). Iba1 immunostaining was performed on brain sections from GFP → WT and CCR2^−/− → WT chimeric mice. Proportion of GFP⁺ cells that were also Iba1⁺ after 4 wk of treatment as counted on the stereological apparatus. (B–E) Representative confocal images reveal apparent co-localization of GFP (green) with Iba1 (red; B and C) and F4/80 (red; D and E) in the corpus callosum of GFP → WT (B and D) and CCR2^−/− → WT chimeric mice (C and E). Merged images are also shown. One representative experiment out of two is shown. n = 4–5 mice/group. ****, P < 0.0001 from an unpaired two-tailed Student’s t test. Bars, 20 µm.