Fig. 1
PDGFRα reporter activity marks skeletal progenitor cells within the periosteum. a–e PDGFRα reporter activity is mainly present in the fibrous layers of the periosteum. a Schematic of the experiment: PDGFRαmT/mG animals (male, aged 2 mo) were administered tamoxifen (TM), and reporter activity was examined after 2 weeks. PDGFRα reporter+ (GFP+) cells were present in the femoral diaphyseal periosteum, as demonstrated by tile scanning (b) and at high magnification (c). Nuclei, DAPI (4′,6-diamidino-2-phenylindole, blue). d Representative histologic appearance of the femoral periosteum observed by H&E staining. e Immunohistochemical staining for Nestin, Gli1, and Lepr within the femoral diaphyseal periosteum using PDGFRαmT/mG reporter sections and detection under a confocal microscope. GFP indicates reporter activity, and Tdtomato expression is not shown. f–j PDGFRα reporter+ periosteal cells give rise to the cambium layer of the periosteum and osteocytes over time. f Schematic of the experiment: PDGFRαmT/mG animals (male, aged 2 mo) were administered TM, and reporter activity was examined after 7 d, 2 mo, 6 mo, and 9 mo. g Representative images of the PDGFRαmT/mG diaphyseal periosteum at different time points after TM injection. Percentage of PDGFRα reporter+ cells in the fibrous periosteum (h), cambium periosteum (i), and osteocytes (j). B bone, PO periosteum. The dashed lines in c, d, e, and g indicate the limit between the inner and outer layers of the periosteum. Scale bars: 500 μm (b) and 50 μm (c, d, e, g). n = 3–4 animals per group. The dot plots represent an individual animal, and the whisker plots indicate the mean and one-SD values. *P < 0.05, **P < 0.01 and ***P < 0.001, as assessed by one-way ANOVA with Tukey’s multiple-comparisons test
