4th Arch Artery Research Articles

Unique vascular morphology of the fourth aortic arches: possible implications for pathogenesis of type-B aortic arch interruption and anomalous right subclavian artery.

Neural crest-derived cells were previously shown to participate in vessel wall formation of the great thoracic arteries, and their contribution was proposed to affect morphology and physiology of these vessels in the chick. The present investigation was undertaken to examine vascular differentiation and morphogenesis of the neural crest-derived aortic arches in mammals. Using immunohistochemical markers for smooth muscle cell differentiation and a neurofilament marker, we examined morphogenesis of the great arteries in mice, ranging from embryonic day 11.5 to the adult. We observed that in the 4th aortic arch arteries early media formation differed from the other arteries, in that they almost completely lacked (or showed decreased) actin expression in certain areas. This discontinuity in actin expression persisted throughout much of foetal development, in the form of circular segments of cells displaying decreased staining for smooth muscle markers, both at the left and right side of the arterial tree. In adult mice, the 4th arch artery derivatives, segment B of the aortic arch and the proximal right subclavian artery, were observed to differ from adjoining vessels in their smooth muscle and elastic composition. Staining for neurofilaments revealed close association of the developing segments with apparent sensory afferent vascular innervation. The unique areas of the 4th arch artery identified here reflect the basic segmental patterning of the early embryonic pharyngeal arches. These segments correlate with sites that are predisposed to interruption or severe hypoplasia, and may thus reveal part of the aetiology of type-B aortic arch interruptions and arteria lusoria.

Relation of the distribution of fibronectin to the obliteration of the arch artery in the chick.

Fibronectin has been believed to be involved in vasculogenesis. This study demonstrates by immunohistochemistry the distribution of fibronectin around the systemic arteries of chick embryos during the periods of aortic arch formation, and examines the possible relationship between the distribution of fibronectin and the obliteration of the arch artery. In embryos at stage 23, no obliteration of arch arteries was recognized on sections. At this stage, intense staining with an anti-fibronectin antibody was seen in the developing tunica media of the carotid artery and dorsal aorta. Staining around the arch arteries was much weaker. At stage 26, the intensity of anti-fibronectin antibody staining was weaker around the left arch artery, although the diameter of the 4th arch artery was not different between the left and right. At stage 27, which is the early period for the obliteration of the left 4th arch artery, the intensity of the anti-fibronectin antibody staining for the left arch artery was much less than that for the right arch artery. These results show that fibronectin does not accumulate around the left 4th arch artery during aortic arch formation and suggest the possibility that a smaller amount of fibronectin is responsible for the obliteration of the left 4th arch artery.