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. 2019 Oct 1;8:e49226. doi: 10.7554/eLife.49226

Figure 1. Soft palate taste papillae as well as hard palate rugae, but not the tongue circumvallate papilla form without innervation.

(A–F) Combined immunohistochemistry for β-III tubulin (Tuj1, brown) and in situ hybridization (blue) for the indicated probes (top panel and left four columns), or immunofluorescence for Prox1 or CK8, combined with immunofluorescence for β-III tubulin and a counterstain with DAPI (two right columns) in wild type (A,B,E) and double Neurog1/2 KO (C,D,F) at E14.5 or E16.5 as indicated. In the circumvallate papilla, markers are expressed on the dorsal surface (white arrowhead for CK8) but not at the lower part of the trenches (red arrowhead in the right column), where taste buds will develop after birth. CK8 is also expressed in flattened cells of the periderm (asterisks). For every probe two animals were examined. CP : circumvallate papilla; FP : fungiform papilla ; PP : palatal papilla ; R : ruga. Scale bars: 20 μm.

Figure 1.

Figure 1—figure supplement 1. Sensory innervation of the oral cavity in Neurog1, Neurog2 and double Neurog1/Neurog2 knockouts.

Figure 1—figure supplement 1.

Anti β-III tubulin immunofluorescence on the palate (top panels) and tongue (bottom panels) of E16.5 mouse embryos of the indicated genotypes. Single Neurog1 or Neurog2 knockouts maintain innervation of the palatal or lingual placodes. Since Neurog2 KO have lost the geniculate, but keep the trigeminal ganglion, the residual innervation of taste organs in these mutants correspond to the somatic (touch and pain) fibers. All innervation, visceral and somatic are lost in double knockouts. Scale bars: 150μm (left column), 20μm (right column).

Figure 1—figure supplement 2. Placodal/papillary gene expression is nerve-independent in fungiform papillae.

Figure 1—figure supplement 2.

Immunohistochemistry for β-III-tubulin combined with in situ hybridization for the indicated genes (left panels), and double immunofluorescence against Prox1 or CK8 and β-III-tubulin counterstained with DAPI (right panel), in the indicated genotypes at E14.5 or E16.5, as indicated. Scale bar, 50 μm.

Figure 1—figure supplement 3. The circumvallate papilla does not form in the absence of visceral innervation.

Figure 1—figure supplement 3.

(A,B) Combined immunohistochemistry and in situ hybridization or immunofluorescence for the indicated markers on coronal (A) or sagittal (B) sections through the circumvallate papilla. (C) Wholemount immunofluorescence on E11.5 embryos showing the absence (asterisk) of the petrosal ganglion (IX) in the Neurog2 KO. X: nodose ganglion.