Figure 6. Comparative expression pattern of new dental genes in developing bearded dragon dentition.

ISH showing the expression of ALX1 (left panels), SIX3 (middle), and ISL1 (right) at various indicated developmental stages in embryonic and early postnatal pleurodont and acrodont dental tissues. As pleurodont teeth are developmentally delayed compared to acrodont teeth (see Figure 1E–P), different embryonic stages were used to attain comparable dental developmental stages in the two dentition types (e.g., 39/24 dpo indicates 39 dpo for pleurodont teeth and 24 dpo for acrodont teeth). The positive signal is false-colored to enhance visibility. High magnifications of the SDL region, as indicated by black outlines, are shown for postnatal teeth (bottom panels). Black arrowheads show relatively higher ALX1 expression in the mesenchymes of embryonic and postnatal pleurodont teeth. In postnatal SDL, ALX1 transcripts are also present in the epithelial compartment (black arrow). Increased ISL1 expression in pleurodont epithelium is only detected at late developmental stages (white arrowheads). Black dashed lines separate the epithelium from mesenchyme. Scale bars: 50 μm (bottom panels); 100 μm (other images).