FIGURE 4.

Expression of Pbx1 in the forming incisor and Meis1/2 expression patterns in embryonic palate, submandibular gland and hair follicle. Incisor cells expressing Meis1 in the incisor also express Pbx1, as the latter is ubiquitously expressed thorough the epithelial and mesenchymal compartments during all stages of incisor development (A–D). At E12.5 Meis1 is expressed in the frontal region of the palate, both in the mesenchymal and epithelial compartments, Meis2 is also expressed in the palatal region and in the tongue (E); Meis1 is not expressed in the posterior region of the oral cavity and Meis2 marks the mesenchymal compartment of the palatal shelves and the tongue (E’). A similar pattern is present at the posterior region of the oral cavity at E13.5 (F). At E14.5 Meis2 is expressed in both epithelial and mesenchymal compartments of the fused palate, as detected using Duplex RNAscope (G) and red-channel RNAscope (H) detection kits. Meis1 and Meis2 are expressed by the forming submandibular gland (I–K), while the hair follicle only expresses Meis2 at E14.5 (L,M). Scale bars 100 μm. Dashed line labels epithelial tissue.