Time-lapse intravital microscopy of BMDCs and macrophages in the tibia. (A) Visualization of BMDCs (red arrows) and macrophages (MCs, white arrows) in the vicinity of the endosteum in vivo using the CX3CR-GFP mouse model, in which these cell types are green. The brown color delineates the SHG signal of the calcified bone (the corresponding movie is available as supplemental Video 2). (B) Quantification of the velocity of BMDCs and MCs in the BM (n = 65 cells per cell type, based on 3 independent experiments). (C) Activity (eg, percentage of cells that present with cell position changing migration) of BMDCs and MCs in the BM, based on 3 independent experiments. (D) Trajectories of individual BMDC and MC movement (n = at least 10 per cell type). (E) Schematic of the grid approach to quantify the distance of the cells to the endosteum, as described in “Methods.” A CFSE-stained transplanted cell (green) is shown in a side view to demonstrate its distance to the calcified bone (brown, autofluorescence). The yellow scale bar from the lower part of the cell body to the bone surface represents the distance to the endosteal surface measured for this cell. All cells were analyzed analogously to obtain distance values. (F) Distance of BMDCs and MCs to the endosteum (vertical bars representing average, n = 65 cells per cell type, based on 3 independent experiments). *P < .05.