(a) Experimental design for the BMT experiment. The BMT mice were treated with 2 weeks of PLX5622 diet and switched to a normal diet for 14 D or 2 Mo for histological analyses. (b) A custom-designed lead helmet used to protect the brain from irradiation damage. Mouse brain was protected by the helmet as shown by the preservation of black fur. (c) Representative images of Iba1+ microglia (red) and GFP+ cells (green) in different brain regions from BMT mice after 14 D and 2 Mo of microglial repopulation. GFP+ cells are highlighted with an open arrowhead and enlarged in the inset highlighted by the dotted circle. (d) Quantification of the percentage of GFP+Iba1+ in repopulated microglia. Quantification was performed using stitched image for the whole coronal section (mean ± SEM). Number of animals used: Ctrl (n = 5), 14 D (n = 5), and 2 Mo (n = 5). (e) GFP+Iba1+ cells shown in choroid plexus and highlighted in the box inset. GFP+Iba1+ cells are highlighted by the dotted circle. Individual numerical values can be found in S1 Data. BMT, bone marrow transplantation; Ctrl, control; D, days; GFP, green fluorescent protein; Iba1, ionized calcium binding adaptor molecule 1; Mo, months; PLX, PLX5622.