Fig. 3

A thin and hypomineralized enamel layer is detected on the Satb1^−/− mouse teeth. The gross morphology shows that the erupted portion of the P13 wt mouse mandibular incisor (a) is larger than the diameter of the erupted portion of the P13 Satb1^−/− mouse mandibular incisor (b). The enamel layer of the Satb1^−/− mouse incisor is more transparent, allowing the underneath dentin to be seen (indicated by blue arrows in b). c X-ray radiographic image of one wt hemimandible shows that well-contrasted mineralized enamel (indicated by red triangles) is easily distinguishable from the dentin on the molars and incisor. In the wt mouse first molar (M1), the root furcation is visible, as marked by the dashed red line. d As to the Satb1^−/− mouse hemimandible, the X-ray radiographic image shows only the dentin to be seen; no furcation is detectable in M1. e Trichrome staining of the wt P13 incisor shows the mineralizing dentin layer stained in blue and enamel layer stained in red/brown. Wild-type secretory ameloblasts (SAB) (f), enamel (e), and dentin (d) are illustrated in the enlarged image. g In the P13 Satb1^−/− mouse incisor, the dentin layer (in blue) had a thickness similar to that of controls, whereas the red/brown enamel layer was hardly visible. h The shortened SAB and significant thinned enamel layer underneath the dentin layer (d) in the Satb1^−/− mouse incisor are further shown in the enlarged image. Scale bars in f and h, 50 μM