Saturday, March 24, 2012: 9:45 a.m. - 11 a.m.
Presentation Type: Poster Session
Objectives: The development of the craniofacial complex involves the interaction between different cell populations, including cells from the neural crest that migrate to the pharyngeal arches and are interacting with the pharyngeal arch ectoderm. Bmp4 is a morphogen that is expressed in both the ectoderm and neural crest cells, initially setting domain proximo-distal boundaries in the mandibular arch and then controlling mandibular and tooth development. Loss of Bmp4 expression in the mandibular arch ectoderm causes severe structural defects, mainly of the distal mandible. However, the effects of ectopic Bmp4 expression on mandibular and tooth development are mostly unknown. Methods: pMes-Bmp4 mice were bred with different Cre transgenic lines to activate Bmp4 expression in the ectoderm or neural crest cell-derived mesenchyme of the mandibular arch. Embryos were collected for skeleton histological and whole mount in situ hybridization analyses. Results: Ectopic activation of Bmp4 in either the ectoderm or neural crest cells produced severe mandibular transformations, including fusion with the upper jaw, absence of ramal elements and an almost complete absence of the mouth opening. Tooth development was also affected in the mutant embryos. Ectopic Bmp4 activation in the ectoderm abolished Fgf8 expression from the ectoderm of the proximal mandibular arch, altering the proximo-distal boundaries of the lower jaw. Conclusion: Bmp4 plays important roles in the development of the mandible and the dentition and the restricted expression of Bmp4 is essential to the normal development of the lower jaw. Supported by NIH/ NIDCR U24 DE16472 (LBR) and T32 DE018380 (YZ), Baylor Oral Health Foundation (ZDA and ELB) and a Research Development Grant (LBR) from the VP Office for Research & Graduate Studies/ Texas A&M Health Science Center.This abstract is based on research that was funded entirely or partially by an outside source: NIH/ NIDCR U24 DE16472 and T32 DE018380
Keywords: Anatomy, Bmp4, Embryology, Genetics and Growth & development