Journal: bioRxiv

Article Title: Anomalous incisor morphology indicates tissue-specific roles for Tfap2a and Tfap2b in tooth development

doi: 10.1101/2020.06.18.157776

Figure Lengend Snippet: Hematoxylin and eosin staining of frontal cryosections showing that duplicated mutant incisors (B, B’) undergo cytodifferentiation at the bell stage similar to I 1 and to control embryos (A, A’). In the mutant without duplicated incisors, a single ventrally curved lower incisor is present and two small upper incisors are present (M, O). In B and B’ the mutant mandibles exhibited ventral curvature (as seen in M, O), preventing the lower incisors and the upper and lower molars from being obtained in the same tissue sections, as in the controls. To ensure comparable planes of section with the controls, mutant hemi-mandibles were tilted backwards during embedding such that the sections through the lower incisors were taken through the anterior-most aspect of the mandible (true frontal plane). Note that only the right or left side of each frontal section is shown. Images taken of the embryos’ right side (A, A’, C, F, G, H) have been mirrored to match images taken of the left side. All histological images taken at 10X magnification. 3-D reconstructions from μCT data show that first and second molars develop in embryos lacking epithelial expression of Tfap2a and Tfap2b (D, E, G, H) and the cusp patterns on M 1-2 (N) and M 1-2 (P) look similar to the control (J: M 1-2 ; L: M 1-2 ). Note that first molars are at the top and second molars are at the bottom. The mutant molars appear slightly shorter anterior-posteriorly than the control but all the main cusps are present. The apparent medial displacement of M 2 / 2 relative to M 1 / 1 in the mutant histological sections (E, H) is likely due to a slightly offset plane of section resulting from the cleft palate and mandible in the mutants. A-H taken at 10X; A’, B’ taken at 40X magnification. Scale bars are 1mm (I, K, M, O), and 0.3mm (J, L, N, P). AM: ameloblasts, OB: odontoblasts, SI: supernumerary incisor, T: tongue.

Article Snippet: Histological staining was performed on cryosections using 10% neutral buffered formalin to post-fix tissue, Mayer’s hematoxylin (Electron Microscopy Sciences), Eosin-Y alcoholic (Fisher Scientific), and Scott’s solution (10g/L MgSO 4 + 2g/L NaHCO 3 + tap water).

Techniques: Staining, Mutagenesis, Expressing

Journal: bioRxiv

Article Title: Anomalous incisor morphology indicates tissue-specific roles for Tfap2a and Tfap2b in tooth development

doi: 10.1101/2020.06.18.157776

Figure Lengend Snippet: Hematoxylin and eosin staining of frontal cryosections show that supernumerary incisors are ventral and slightly posterior to I 1 at this stage. Representative sections of incisors from 2 individuals are shown (B+C, D+E). Note the attachment of the supernumerary incisors to the ventral epithelium (C, E, arrowheads) while I 1 in the mutants (B, D) and controls (A) is attached to the dorsal dental lamina (arrowheads). Molars in mutant embryos vary slightly among individuals from early cap (H, K) to late cap stage (G, J). Aberrant appearance of molar teeth in frontal sections of Tfap2 mutant embryos may be due to slight displacement of the molars along the medial-lateral axis relative to the plane of section as a result of cleft palate. SI: supernumerary incisor, MC: Meckel’s cartilage. Note that only the right or left side of each frontal section is shown. Images taken of the embryos’ right side (A, G, H, J, K) have been mirrored to match images taken of the left side. Images taken at 20X magnification.

Article Snippet: Histological staining was performed on cryosections using 10% neutral buffered formalin to post-fix tissue, Mayer’s hematoxylin (Electron Microscopy Sciences), Eosin-Y alcoholic (Fisher Scientific), and Scott’s solution (10g/L MgSO 4 + 2g/L NaHCO 3 + tap water).

Techniques: Staining, Mutagenesis

Journal: bioRxiv

Article Title: Anomalous incisor morphology indicates tissue-specific roles for Tfap2a and Tfap2b in tooth development

doi: 10.1101/2020.06.18.157776

Figure Lengend Snippet: Hematoxylin and eosin stained cryosections in the frontal plane showing cap stage (E14.5) incisors (A, B, D, E) and molars (C, F) look similar in the mutant (D-F) and the control (A-C) embryos. Note that only the right or left side of each frontal section is shown. An image taken of the embryos’ right side (C) has been mirrored to match the corresponding images of the left side. Due to the clefted palate, the anterior frontal section (D) is angled on the medial aspect of the premaxilla. 3-D reconstructions of μCT data show that the upper molars (L: M 1-2 ) and lower molars (N: M 1-2 ) in the mutant appears shorter compared to the control (H: M 1-2 ; J: M 1-2 ) but all major cusps are present. Note the midface cleft in the mutant (K) outlined in white, compared to the control (G). A-F taken at 10X magnification. Scale bars are 1mm (G, I, K, M) and 0.3mm (H, J, L, N). Pmx: premaxilla, Mx: maxilla, Md: mandible, T: tongue.

Article Snippet: Histological staining was performed on cryosections using 10% neutral buffered formalin to post-fix tissue, Mayer’s hematoxylin (Electron Microscopy Sciences), Eosin-Y alcoholic (Fisher Scientific), and Scott’s solution (10g/L MgSO 4 + 2g/L NaHCO 3 + tap water).

Techniques: Staining, Mutagenesis