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

Figure 1. Different types of bearded dragon teeth develop through morphologically equivalent stages.

Figure 1.

(A, B) Micro-CT scan images of bearded dragon skull at hatchling stage in frontal (A) and lateral (B) views. Insets show high magnifications of anterior pleurodont (A) and posterior acrodont (B) teeth. Hatchling bearded dragons possess four pleurodont teeth (one in each jaw quadrant; white arrowheads) and one central egg tooth (red arrow). Scale bars: 1 cm (main images); 2.5 mm (insets). (C, D) 3D volume rendering as well as tooth (C, D; orange) and dental lamina (DL) (D); blue) segmentation of PTA-stained juvenile bearded dragon upper jaw in ventral views, showing the morphogenesis (C), red arrows) or replacement (C), white arrowheads) of anterior pleurodont teeth. Only the segmented teeth and DL are shown in panel (D) to highlight the expansion of the DL along the oral-aboral axis at pleurodont tooth positions (white arrows). Scale bars: 1 mm. (E–P) Hematoxylin and eosin (H and E)-stained coronal (E–J) or sagittal (K–P) sections of developing acrodont (E–J) and pleurodont (K–P) teeth at various developmental stages indicated as embryonic days post-oviposition (dpo) or days post-hatching (dph). Vestigial teeth develop directly from the oral epithelium (OE) prior emergence of functional dentition (E; asterisk). Pleurodont teeth emerge later in development than acrodont teeth, and the DL connecting the pleurodont tooth germs to the OE surface is extended (L, M; red arrows). The acrodont successional dental lamina (SDL) starts to develop at late mineralization stage and persists until hatching (I, J; white arrowheads), while the pleurodont SDL is only visible around hatching time (O, P; black arrowhead). Scale bars: 100 μm.