CELLULAR AND MOLECULAR CONTRIBUTIONS OF THE CARDIAC NEURAL CREST TO CARDIOVASCULAR DEVELOPMENT

Normal development of the heart and great arteries requires participation of the cardiac neural crest. Ectomesenchymal cells from this area of the neural crest migrate to pharyngeal arches 3, 4, and 6, where they support development of the aortic arch arteries. Cells continue migration from the pharyngeal arches to specific sites in the outflow tract. Removal of the neural crest results in two types of malformations: outflow septation defects and alignment defects. The genesis of these two types of defects is by two different mechanisms. Outflow septation is disturbed when a critical number of cells does not reach the outflow tract. Alignment is altered by an as yet unknown secondary mechanism that is transmitted upstream to the heart from the pharyngeal arches. Aortic arch artery and ventricular development as well as hemodynamic parameters are abnormal from an early age. Some possible molecular mechanisms involved in specifying neural crest for participation in heart development are discussed.