Figure 2
Expression of FAM20A in the mouse dental tissues. (a) X-Gal staining revealed the presence of FAM20A signals in the odontoblasts (arrowhead) of the mandibular incisors and its total absence from the first molars (M1) of the Fam20AlacZ-flox/+ mice at 17.5 days post coitum. (b) At postnatal day 0 (P0), FAM20A signals were observed in the odontoblasts (arrowhead) but not in the ameloblasts (arrow) of the mandibular first molar (M1); at this stage, FAM20A signals were also observed in the secretory stage ameloblasts (green arrow) in the incisor; (b1) higher magnification view of the box area in b. (c) At P1, the FAM20A signals in the odontoblasts (arrowhead) were stronger than in the ameloblasts (arrow). (d) At P5, the FAM20A signals in the ameloblasts (arrow) of some regions were stronger than in the odontoblasts (arrowhead); relatively strong FAM20A signals were also observed in some cells of the stellate reticulum (asterisk). (e) At P7, the intensity of FAM20A signals in the ameloblasts (arrow) was similar to that in the odontoblasts (arrowhead). (f) At P11, FAM20A signals were present in the reduced enamel epithelium (arrows) and odontoblasts (arrowhead) in the Fam20AlacZ-flox/+ mice. (g) Wild-type mice did not show any X-Gal-positive staining. (h) Immunohistochemistry showed weak anti-FAM20A immunoreactivity in the ameloblasts (arrow) and the odontoblasts (arrowhead) of the mandibular first molar at P1. (i) At P5, strong anti-FAM20A immunoreactivity was observed in the first molar ameloblasts (arrow), odontoblasts (arrowhead) and stellate reticulum (asterisk); (i1) higher magnification view of the box area in i revealed that, in the ameloblasts, FAM20A protein was almost exclusively located in the cytoplasm on the enamel matrix side of the nuclei. (j) Immunohistochemistry staining with the first antibody-free control showed no FAM20A signal in the ameloblasts (arrow) or odontoblasts (arrowhead). (k) In situ hybridization analyses showed that, at 17.5 days post coitum, FAM20A mRNA was not observed in any of the tooth germs but was observed in the tongue root region (arrow). (l) At P1, FAM20A mRNA was observed in the ameloblasts (arrow) and in the odontoblasts (arrowhead) of the mandibular first molar. (m) At P11, FAM20A mRNA was present in the reduced enamel epithelium (arrows) and odontoblasts (arrowhead) of the first molar. (a–g) X-Gal staining of the mouse mandible; (h–j) anti-FAM20A IHC staining of the first molar region in the mouse mandible; (k–m) in situ hybridization staining of mouse head and jaw bones. Scale bars, 200 μm (a and b); 50 μm (b1); 10 μm (i1); 500 μm (k); 200 μm (l and m); 100 μm (all other images). P0, P1, P5, P7 and P11 are abbreviations of postnatal day 0, 1, 5, 7 and 11, respectively. Ctrl, control; d.p.c., days post coitum; IHC, immunohistochemistry; Inc, incisor; ISH, in situ hybridization.
