CD45Cre-labeled murine BM. (A) IF-stained metaphyseal bone sections (20×) of RFP-labeled CD45Cre mouse showing BM at homeostasis. White arrows indicate a red CD45-derived cell that resides near the endosteal region. Green CD45 stain reveals that the cell no longer expresses CD45. (B) IF metaphyseal section (40×) of BM from DsRed-labeled CD45Cre mouse crossed with a Col2.3GFP mouse, which GFP labels mature osteoblast. White arrowhead indicates the red CD45-derived cell; green arrowhead indicates the GFP-labeled mature osteoblast. (C) Confocal Z-stack image (63×) showing RFP Vav1-derived cell that does not stain for lineage markers (B220, CD3, Ter119, Gr1, CD11b). (D) Flow cytometric analysis of transgenic CD45/Ai9 mouse BM and bone-lining cells gated on DsRed⁺/CD45^– population. (E) Dot plot and histogram depiction of transgenic CD45/Ai9 mouse BM and bone-lining cells gated on DsRed⁺/CD45^– population showing shift of F4/80 expression. F4/80 expression on dot plot showed an average of 17.27% ± 3.6% positivity vs 1.1% ± 0.015% in unstained controls. (F) Flow cytometric analysis of WT mouse BM and bone-lining cells gated on CD45^– population. F4/80 expression on dot plot analysis showed an average of 13.5% ± 0.8% positivity vs 1.1% ± 0.015% in unstained controls.