Fig. 5

Collagen expression in osteoblasts of gar and zebrafish is equivalent. A, Trichrome-stained coronal gar section. B, confocal slice of sp7:EGFP; foxp2.A:EGFP zebrafish, which have GFP expression in both developing osteoblasts and developing chondrocytes, respectively [45, 46] and also are stained with Alizarin red to visualize mineralized bone matrix. C-J, in situ hybridization on coronal sections. Aniline blue staining in the 14 dpf gar (A) and Alizarin red staining in the 6 dpf zebrafish (B) reveals bone matrix of the dentary. Osteoblasts of the zebrafish dentary are labeled with the sp7:EGFP transgene. Osteoblasts of both the gar and zebrafish dentaries expressed col1a2 (C, D), col2a1 (E, F), col10a1 (G, H), and col11a2 (I, J), although expression of col2a1a in zebrafish osteoblasts was relatively lower than seen in gar osteoblasts. Scale bars: A-J = 15 µm. Abbreviations: b = bone; c = cartilage; dpf = days post-fertilization; ob = osteoblast; Tri = Trichrome.