Abstract
Normal development of the heart and great arteries requires the contribution 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 and give rise to connective tissues. The cells continue their migration from the pharyngeal arches to specific sites in the outflow tract of the heart. Removal of the neural crest before migration results in two major types of malformations: truncal septation defects and aortic arch anomalies. Truncal septation is disturbed when the cells do not reach the outflow tract. Patterning of the aortic arch arteries is perturbed when the cells do not form connective tissue and tunica media to support the aortic arch arteries. With the advent of genetically based animal models with cardiovascular anomalies, some of which are neural crest related, it becomes important to understand what we know from ablation studies and which questions remain. Some possible molecular mechanisms involved in specifying the neural crest and/or outflow tract for participation in heart development are discussed.