Fig. 3

FGF signaling was overactivated in the GAG-deficient incisors. A–D In situ hybridization of E12.5 whole mount mandibles. A′–D′ Coronal sections through the dashed white lines in (A–D). The yellow dotted lines indicate the border between the dental epithelium and the dental mesenchyme. d↔m indicates the orientation of distal and mesial sides. In the GAG-deficient incisors, Pax9 was upregulated at the mesial side of dental mesenchyme (arrow), and Etv5 showed stronger expression in both the dental epithelium and the dental mesenchyme. E, F Immunohistochemistry staining of sagittal sections of E13.0 lower incisors showed an upregulation of p-ERK in both the dental epithelium and dental mesenchyme in the Fam20B-deficient incisors (white arrows). lb↔lg indicates the orientation of labial and lingual sides. Scale bars: 250 μm in whole mount A–D; 50 μm in sections A′–D′ and E, F