Figure 1.

Loss of Hoxa2 leads to increased osteogenic differentiation of the palatal mesenchyme at E16.5. Position matched coronal sections of wild-type and Hoxa2^−/− embryos at E16.5 were stained for ALPI (A–H), RUNX2 (I–L), and SP7 (M–P). Sections in the anterior region (A,B,E,F,I,J,M,N) were through the middle of the first molar tooth bud to detect osteogenic condensation of the palatal process of the maxilla. Sections in the posterior region (C,D,G,H,K,L,O,P) were through the osteogenic centers of the developing palatal process of the palatine bone. (A–D) ALPI staining (blue) counterstained with nuclear fast red. Scale bar, 100 μm. Boxed regions in (A–D) highlighting the palate are enlarged (E–H). Scale bar, 50 μm. (E,F) In the anterior hard palate, ALPI staining in the two condensations of the palatal process of the maxilla (marked in black dotted lines) was evidently increased in the Hoxa2^−/− embryos (F) compared to wild-type (E). (G,H) In the posterior hard palate, ALPI stained developing palatal process of the palatine bone (marked in black dotted lines) in the Hoxa2^−/− embryos (H) was increased compared to the wild-type (G), n = 5 biological replicates. (I–P) Immunohistochemical analyses of RUNX2 (green; I–L) and SP7 (red; M–P) in wild-type and Hoxa2^−/− palate at E16.5. RUNX2 was increased in both anterior (J) and posterior regions (L) of the Hoxa2 null hard palate, whereas SP7 was increased only in the anterior hard palate (N), n = 4 biological replicates. Scale bar, 50 μm. M1, first molar; Mb, mandible; Mx, maxilla; NS, nasal septum; pppb, the palatal process of the palatine bone; ppmx, the palatal process of the maxilla; T, tongue.