Fig. 3

The tenogenesis and myogenesis in Osr2-cre; Rosa26R-Fgf8 masseter. a, a’ The cross views of E13.5 Osr2-cre;Rosa26R-mT/mG mice at the deep (a) and superficial (a’) masseter tendons. b, b’ The cross views of E13.5 Osr2-cre; Rosa26R-mT/mG; Rosa26R-Fgf8 mice at the deep (b) and superficial (b’) masseter tendons. The asterisks in b and b’ delineated the tenogenic mesenchyme of masseters. c, c’ The cross views of E15.5 Osr2-cre;Rosa26R-mT/mG mice at the deep (c) and superficial (c’) masseter tendons. The white arrows in c and c’ delineated the masseter tendons. d, d’ The cross views of E15.5 Osr2-cre; Rosa26R-mT/mG; Rosa26R-Fgf8 mice at the deep (d) and superficial (d’) masseter tendons. The asterisks in d and d’ delineated the tenogenic mesenchyme of the masseters. The blue dashed lines circled the mandibular bones, while the white dotted boxes delineated masseter, which were magnified in the left-lower of each image. (T: Tongue; Ps: Palatal Shelves). e–j In situ hybridization showed the tenogenic markers and extracellular matrix gene expression in the E14.5 WT and Osr2-cre; Rosa26R-Fgf8 masseter tendons. The Scx expression in the masseter tendons of the E14.5 WT (e) and Osr2-cre; Rosa26R-Fgf8 mice (f). The Tenomodulin expression in the masseter tendons of the E14.5 WT (g) and Osr2-cre; Rosa26R-Fgf8 mice (h). The blue dotted lines in e–h circled the mandibular bones. The Tenascin C expression in the masseter tendons of the E14.5 WT (i) and Osr2-cre; Rosa26R-Fgf8 mice (j). The black arrowheads in e, g and i pointed to the masseter tendons in E14.5 WT mice, while the red arrowheads in f, h and j pointed to the masseter tendons in E14.5 Osr2-cre; Rosa26R-Fgf8 mice. (Scale bars: 200 μm). k–n The Masson staining and immunohistochemical staining with antibody against Myosin in the WT and Osr2-cre; Rosa26R-Fgf8 mandibles. k, l The Masson staining showed the morphology of the tendon and myofibers in the E13.5 WT (k) and Osr2-cre; Rosa26R-Fgf8 masseters (l). The images in the left-lower of k and l showed the Myosin immunostaining of the masseters in the dashed boxes of k and l, respectively. m, n The Masson staining showed the morphology of the tendon and myofibers in the E16.5 WT (m) and Osr2-cre; Rosa26R-Fgf8 masseters (n). The images in the left-lower of m and n showed the Myosin immunostaining of the masseters in the dashed boxes of m and n, respectively. Scale bars: 200 μm