AbstractBlood flow patterns have been outlined in the chick embryo heart. The initial flow pattern adapts to the heart form but soon vascular forces affect cardiogenesis. Spiralling of the blood streams in the sinus venosus appears to lead to an expansion of this chamber. The atrial septum forms between parallel streams and evidence is presented that blood flow contributes to septation. Interatrial flow develops with a fusion of the inflow streams bringing the entire systemic venous return into the right atrium when the left atrium receives a small pulmonary return; the difference in pressures is believed to lead to perforation of the septal wall.The ventricular septum also forms between parallel bloodstreams. Inhibition of the left ventricular outflow, brought about by the application of trypan blue to the embryos, was associated with the production of ventricular septal defects. Higher pressures in the left ventricles, brought about by increased vascular resistance to these chambers, led to the defects as evidenced by left to right flow through the defects. An interpretation of the origin of this common congenital anomaly is thus offered.
展开▼
