CARDIAC NEURAL CREST IS ESSENTIAL FOR THE PERSISTENCE RATHER THAN THEFORMATION OF AN ARCH ARTERY

Double-label immunohistochemistry was used to compare early aortic arc h artery development in cardiac neural crest-ablated and sham-operated quail embryos ranging from stage 13 to stage 18. The monoclonal antib ody QH-1 labeled endothelial cells and their precursors, and HNK-1 lab eled migrating neural crest cells, In the sham-operated embryos, the t hird aortic arch artery developed from a lumenizing strand of endothel ial precursors that became separated from the pharyngeal endoderm by m igrating cardiac neural crest cells as they ensheathed the artery. The arch artery of the neural crest-ablated embryos lumenized but failed to become separated from the pharyngeal endoderm, indicating that neur al crest is unnecessary for the early formation of the aortic arch art ery. However, once blood flow was initiated through the third arch art ery of crest-ablated embryos at stage 16, the artery became misshapen and sinusoidal. By embryonic day 3, abnormal connections to the dorsal aorta occurred and bilateral symmetry was lost, suggesting that the l oss of neural crest-derived ectomesenchyme destabilizes the nascent ar tery, Although here we show no loss of the third arch artery, past stu dies have reported hypoplasia or missing carotids in older neural cres t-ablated embryos (Bockman et al, [1987] Am. J. Anat. 180:332-341; Boc kman et al. [1989] Anat. Rec. 225:209-217; Nishibatake et al. [1987] C irculation 75:255-264; Tomita et al. [1991] Circulation 84:1289-1295), We suggest that the cardiac neural crest is essential for the persist ence of an arch artery, but not its formation. Furthermore, since chan ges in the development of the arch artery are seen prior to the format ion of the tunica media, it is suggested that a critical period is rea ched in the development of the arch artery, after lumenization, but pr ior to the formation of the tunica media, which necessitates the prese nce of the cardiac neural crest. (C) 1996 Wiley-Liss, Inc.