Fig. 1.

Engrafted brain macrophages accumulate over time and self-maintain. a Schematic of tandem BM transfer protocol. b Flow cytometric blood monocyte analysis of chimera 16 weeks post second transplantation. c Flow cytometric analysis of myeloid brain cells 16 weeks post second BMT revealing host microglia (CD45.1/2⁺, blue), cells derived from the first graft (CD45.1⁺ GFP⁺, red) and cells derived from the second graft (CD45.2⁺ RFP⁺, orange). d Distribution of host and graft-derived cells out of the total Ly6C/G (Gr1)^– CD45^lo CD11b⁺ cells in brain and spinal cord at two time points. Data are a summary of six mice. e Histological analysis 7 weeks post second BMT revealing ramified GFP⁺ and RFP⁺ cells with microglia morphology (scale bar 20 μm). Representative picture