Whole-mount tissue preparation of sternal bones was performed as described (Kunisaki et al., 2013 (link)). In brief, sternal bones from tamoxifen-induced Pdzk1ip1-CreER R26SW were isolated, transected into two to three fragments and sagittally bisected to expose the BM. The tissues were fixed in 4% paraformaldehyde for 1 h at 4°C, stained with biotinylated anti-CD48 (HM48-1; BioLegend), rat anti-mouse CD41 (MWReg30; BioLegend), and biotinylated lineage markers (anti-Ter119 [TER119], anti-B220 [6B2], anti-Gr1 [RB6-8C5], anti-CD3e [500A2], anti-CD11b [HM1/70]; eBiosciences). Secondary reagents included Alexa Fluor 647–conjugated goat anti-rat IgG and Alexa Fluor 488–streptavidin conjugate (Life Technologies). Tissues were imaged on a 35-mm glass-bottom dish using a Zeiss LSM 710 confocal microscope.