Embryonic and early postnatal cranial bone volume and tissue mineral density values for C57BL/6J laboratory mice. Issue 7 (7th February 2022) - Lesciotto, Kate M.
Abstract: Background: Laboratory mice are routinely used in craniofacial research based on the relatively close genetic relationship and conservation of developmental pathways between humans and mice. Since genetic perturbations and disease states may have localized effects, data from individual cranial bones are valuable for the interpretation of experimental assays. We employ high‐resolution microcomputed tomography to characterize cranial bones of C57BL/6J mice at embryonic day (E) 15.5 and E17.5, day of birth (P0), and postnatal day 7 (P7) and provide estimates of individual bone volume and tissue mineral density (TMD). Results: Average volume and TMD values are reported for individual bones. Significant differences in volume and TMD during embryonic ages likely reflect early mineralization of cranial neural crest‐derived and intramembranously forming bones. Although bones of the face and vault had higher TMD values during embryonic ages, bones of the braincase floor had significantly higher TMD values by P7. Conclusions: These ontogenetic data on cranial bone volume and TMD serve as a reference standard for future studies using mice bred on a C57BL/6J genetic background. Our findings also highlight the importance of differentiating "control" data from mice that are presented as "unaffected" littermates, particularly when carrying a single copy of a cre‐recombinase gene. Key Findings: Higher average volume and density of cranial neural crest‐derived and intramembranously‐forming bones during embryonic development. Higher average density in bones of the braincase floor during early postnatal development. Ontogenetic data on cranial bone volume and TMD serve as a reference standard for mice bred on a C57BL/6J genetic background.