Localization of MPP subsets in structurally distinct regions of bone marrow. (A) Spatial designation of bone marrow in femurs. Endosteal region is determined, as previously described.30 The central marrow region30 between the endosteum and central sinus is further divided into 2 regions, as shown in this figure. The borders of each region are indicated with white dotted lines. The section was stained with DAPI (blue). Original magnification of the image is ×20. (B) Three different localization patterns of injected MPPs to the inner region (section 1), outer region (section 2), and endosteal region (section 3). Arrows indicate the injected GFP+ cells (green). (C) Localization of VCAM-1+ and VCAM-1− MPPs to the distinct regions in bone marrow. At least 30 cells from each population were counted. Representative results from 3 independent experiments were shown. *P < .05 (statistical significance) in the distribution of injected cells to the 3 regions by χ2 test. (D) VCAM-1− MPPs and GMPs localize to distinct regions in the bone marrow after intravenous injections into nonirradiated wild-type mice. Localization of injected cells was examined, as in panel C. One result from 2 replicate experiments was shown. *P < .05 (statistical significance) by χ2 test.
