147 - Integrating Microcomputed Tomography and Histology to Construct a 3D Model of the Lower Jaw in C57BL/6J Mice

Poster Board Number: 147
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Abstract Body : Mandibulofacial anomalies may be visible in early stages of embryogenesis, including in the formation of Meckel’s cartilage (MC), a rod-like structure historically described as a template for the developing mandibular bone. While birth defects of the mandible and growth, ossification, and loss of MC have been well studied, the precise spatial and temporal relationship between the bone, teeth, and cartilage of the lower jaw is poorly understood. This research integrates analyses of histological serial sections and phosphotungstic acid (PTA)-enhanced microcomputed tomography (PTAe microCT) to quantitatively describe growth in length and curvature of MC, and its relationship with the developing mandibular bone and teeth. We do this for two distinct developmental stages, embryonic day 15.5 (E15.5) and the day of birth (P0) in C57BL/6J mice. Manual segmentation and sparse annotations of cartilage, bone, and teeth using Avizo 2021.2 (ThermoFisher Scientific) informed deep learning algorithms. Results were used to reconstruct the three-dimensional relationship between MC, ossifying mandibular bone, and the developing dentition. The volume of MC was estimated using the MaterialStatistics module of Avizo and total length of the long axis was estimated using the curve function of 3D Slicer (version 5.2.1). Because histological analysis provides information pertaining to the functional relationship among cells and tissues and microCT provides a 3D atlas of morphological correspondence, the two resources can be combined to increase our understanding of the 3D relationship among tissues and cells during developmental processes. Our data demonstrate the 3D differences in length and volume in MC, teeth, and mandibular bone between E15.5 and P0, the changing anatomical relationship between cartilage and mineralized tissues of the jaw during this developmental period, and prompt hypotheses about the functional relationship among these developing tissues. The study also serves as a reference for future research merging micro-CT images with histological serial sections. This study was funded in part by grants from NIH/NIDCR: R01DE027677, R01DE031439, and R01DE 029832.