Fig. 2.

Stat3 is required in limb mesenchymal cells for osteoblast differentiation and bone formation. (A–E) Representative images of Sp7 IF staining (A), Col1a1 in situ hybridization (B), Opn IF staining (C), von Kossa staining (D), and Mmp13 in situ hybridization (E) of the humerus sections from E16.5 littermate embryos or P0 littermate pups with indicated genotypes. The arrows indicate reduced osteoblast marker (protein/gene) expression or ossification. The arrowheads indicate bone fractures in the P0 mutant humerus. (Scale bars, 100 µm.) (F) Western blotting analyses of the humerus bone tissue lysates of the P0 pups with indicated genotypes. (F’) Quantification of the Western blotting results in (F). (G) Representative µCT images of femurs from 5-wk-old littermate mice with the indicated genotypes. (Scale bars, 1 mm.) (H) Quantification of humerus length (n = 3, mean ± SD). (I and J) Representative µCT images of the cortical (I) and trabecular (J) femur bones from 5-wk-old littermate mice. (Scale bars, 100 µm.) (K–M) Quantification of indicated parameters of µCT scanning. (N–P) Histomorphometric analysis of bone formation from 5-wk-old littermate mice of indicated genotypes. Representative images of double Calcein labeling in the distal femur heads (N), cortical bones (O), and trabecular bones (P) of the indicated genotypes. (Scale bars, 100 µm.) (Q) Quantification of indicated histomorphometric parameters of the distal femurs from 5-wk-old littermate mice of indicated genotypes. *P < 0.05, **P < 0.01, and ***P < 0.001 were considered significant; ns, not significant. The data are shown as means ± SD.