Background Given the need for descriptive and increasingly mechanistic morphological analyses, contrast‐enhanced microcomputed tomography (microCT) represents perhaps the best method for visualizing 3D biological soft tissues in situ. Although staining protocols using phosphotungstic acid (PTA) have been published with beautiful visualizations of soft tissue structures, these protocols are often aimed at highly specific research questions and are applicable to a limited set of model organisms, specimen ages, or tissue types. We provide detailed protocols for micro‐level visualization of soft tissue structures in mice at several embryonic and early postnatal ages using PTA‐enhanced microCT. Results Our protocols produce microCT scans that enable visualization and quantitative analyses of whole organisms, individual tissues, and organ systems while preserving 3D morphology and relationships with surrounding structures, with minimal soft tissue shrinkage. Of particular note, both internal and external features of the murine heart, lungs, and liver, as well as embryonic cartilage, are captured at high resolution. Conclusion These protocols have broad applicability to mouse models for a variety of diseases and conditions. Minor experimentation in the staining duration can expand this protocol to additional age groups, permitting ontogenetic studies of internal organs and soft tissue structures within their 3D in situ position.
Forensic anthropologists anticipated a significant impact from the 1993 Supreme Court Daubert decision, which addressed the standard of admissibility for expert testimony. In response, many forensic articles cited Daubert in the search for objective techniques or a critique of established subjective methods. This study examines challenges to forensic anthropological expert testimony to evaluate whether Daubert has actually affected the admissibility of such testimony. Thirty cases were identified that addressed the admissibility of the testimony, including 14 cases prior to Daubert and 16 after Daubert. Examination of these cases indicates that post-Daubert cases do not result in more exclusions. Yet, this lack of exclusions may instead be viewed as a manifestation of the field's overall surge toward more objective and quantifiable techniques in a self-regulating response to Daubert.
Dramatic changes in cranial capacity have characterized human evolution. Important evolutionary hypotheses, such as the spatial packing hypothesis, assert that increases in relative brain size (encephalization) have caused alterations to the modern human skull, resulting in a suite of traits unique among extant primates, including a domed cranial vault, highly flexed cranial base, and retracted facial skeleton. Most prior studies have used fossil or comparative primate data to establish correlations between brain size and cranial form, but the mechanistic basis for how changes in brain size impact the overall shape of the skull resulting in these cranial traits remains obscure and has only rarely been investigated critically. We argue that understanding how changes in human skull morphology could have resulted from increased encephalization requires the direct testing of hypotheses relating to interaction of embryonic development of the bones of the skull and the brain. Fossil and comparative primate data have thoroughly described the patterns of association between brain size and skull morphology. Here we suggest complementing such existing datasets with experiments focused on mechanisms responsible for producing the observed patterns to more thoroughly understand the role of encephalization in shaping the modern human skull.
A number of textbooks, review articles, and case reports highlight the potential comorbidity of choanal atresia in craniosynostosis patients. However, the lack of a precise definition of choanal atresia within the current craniosynostosis literature and widely varying methods of detection and diagnosis have produced uncertainty regarding the true coincidence of these conditions. The authors review the anatomy and embryologic basis of the human choanae, provide an overview of choanal atresia, and analyze the available literature that links choanal atresia and craniosynostosis. Review of over 50 case reports that describe patients diagnosed with both conditions reveals inconsistent descriptions of choanal atresia and limited use of definitive diagnostic methodologies. The authors further present preliminary analysis of three-dimensional medical head computed tomographic scans of children diagnosed with craniosynostosis syndromes (e.g., Apert, Pfeiffer, Muenke, and Crouzon) and typically developing children and, although finding no evidence of choanal atresia, report the potentially reduced nasal airway volumes in children diagnosed with Apert and Pfeiffer syndromes. A recent study of the Fgfr2c Crouzon/Pfeiffer syndrome mouse model similarly found a significant reduction in nasal airway volumes in littermates carrying this FGFR2 mutation relative to unaffected littermates, without detection of choanal atresia. The significant correlation between specific craniosynostosis syndromes and reduced nasal airway volume in mouse models for craniosynostosis and human pediatric patients indicates comorbidity of choanal and nasopharyngeal dysmorphologies and craniosynostosis conditions. Genetic, developmental, and epidemiologic sources of these interactions are areas particularly worthy of further research.
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