CERVICAL FLEXION - ITS CONTRIBUTION TO NORMAL AND ABNORMAL CARDIAC MORPHOGENESIS

Although His in 1881 and Patten in 1922 suggested that cervical flexio n could play an important role in normal cardiac morphogenesis, until recently this hypothesis has been largely neglected. The purpose of th is report is to present data indicating that prevention of cervical fl exion leads to double outlet right ventricle (DORV), which is unrelate d to any affect on neural crest cell migration. At stage 11-12, suture material was inserted into the neural tube to prevent cervical flexio n. Six out of 22 experimental embryos survived until stage 38 and 5 ou t of 6 had DORV. Neither abnormalities of the aortico-pulmonary septum nor interruption of the aortic arch were observed at dissection. Hemo dynamic studies performed at stage 18 revealed distinctive characteris tics that are inconsistent with hemodynamic studies previously reporte d following neural crest ablation. With respect to immunohistochemical studies using neural crest associated antigen HNK-1 antibody, normal migration of neural crest cells was noted in the outflow tract in the experimental embryos at stage 22. These hemodynamic and immunohistoche mical studies suggest that insertion of suture material into the neura l tube at stage 11-12 does not jeopardize neural crest migration. We p ropose that reduction in cervical flexion increases the distance betwe en the future aorta and the left ventricle, which prevents the transit ion of intracardiac flow pattern from a serial circulation to a parall el one, leaving persistence of a ''double outlet'' from the right vent ricle. (C) 1996 Wiley-Liss, Inc.