关键词：
Developmental biology
Veterinary science
Molecular biology
摘要：
Affecting approximately 1-in-700 live births, “orofacial clefting” represents the most common class of craniofacial birth defect. Although not a major cause of mortality, these conditions pose significant problems for those affected, including necessary surgical interventions, psychological difficulty and a higher mortality risk. Epidemiological studies of populations affected by clefting, combined with genetic analyses, have identified candidate genes, genomic regions of interest as well as environmental risk factors. Analyses of these factors in mouse models has provided insight into craniofacial morphogenesis. Concurrently, novel factors, discovered through mouse mutagenesis, have been identified in affected human populations. Using modern imaging techniques, overt clefting has been revealed to be part of larger phenotypic spectrum. For this reason, detailed morphological studies of mouse-mutants with craniofacial phenotypes are necessary for effective modeling and comparisons to be made. The Pbx genes (Pbx 1-2-3), TALE homeodomain-containing transcription factors, are believed to play integral roles in the development of many organ systems including the midfacial complex. By immunofluorescence antibody assay, this study provides the first detailed analyses of how Pbx1 & Pbx2 are expressed temporally and spatially in the developing murine midface, over the developmental time-period critical for development of the lip, primary and secondary palates (E10.5 to E13.5). Pbx1&2 expression was observed in epithelium and mesenchyme from the very earliest stages of facial morphogenesis, and into the later stages of palatal development. Excision of Pbx1 from the cephalic epithelium or pre-migratory Cranial Neural Crest cells revealed highly distinct and temporally divergent phenotypes. For the cephalic epithelial mutant (Pbx1fl/fl ; Pbx2wt, FoxG1Crewt/+), cleft lip, extending into the primary palate with clefting of the secondary palate was the primary observation, whereas
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