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. 2019 Aug 16;8:e47702. doi: 10.7554/eLife.47702

Figure 2. Expression of conserved dental genes is maintained from embryonic development to replacement.

Figure 2.

(A) In situ hybridization (ISH) showing the expression of SHH, PITX2, NOTCH1, and LEF1 at various indicated developmental stages (24, 28, and 48 dpo) in developing mandibular acrodont teeth. The positive signal is false-colored to enhance visibility. Insets at 48 dpo show high magnifications of the SDL region indicated by black outlines. Black arrowheads indicate the expression of PITX2 and LEF1 in both the primary DL (24 dpo) and SDL (48 dpo). Black arrows indicate the expression of NOTCH1 in the OE, and red arrows show the expression of SHH in the inner enamel epithelium of both vestigial and functional teeth. (B) PCNA immunohistochemistry (IHC) and TUNEL apoptotic assay (left panels; red staining), SOX2 IHC (middle panel; red staining), or PITX2 and LEF1 ISH (right panels) in parallel sections of pleurodont (top panels) and acrodont (bottom) SDL in juvenile bearded dragon (<1 year old). Arrowheads and asterisks indicate focal or absent expression in the SDL tip of pleurodont teeth, respectively. Arrows show positive apoptotic cells in mesenchymal tissues. (C) BrdU IHC (green) in pleurodont (top panel) and acrodont (bottom) SDL in adult bearded dragon (>2 years old) following a 7 day BrdU pulse. The epithelium-mesenchyme junction is indicated by black or white dashed lines in all panels (A–C), and cell nuclei are counterstained with DAPI (blue staining) in IHC and TUNEL experiments (B, C). Scale bars: 100 μm.