Changes

===Ventricular Outflow Septation===

===Ventricular Outflow Septation===

At this stage the ventricles have one common outflow tract.

At this stage the ventricles have one common outflow tract, the anterior side of the tract being the Truncus arteriosis and the postierior side being the Conus cordis. A pair of subendothelial swellings appear on either side of the tract and eventually fuse to form a setpum, dividing the outflow tract into an aortic trunk and a pulmonary trunk. The septum takes on a spiral form so that blood from the left ventricle is directed into the aortic trunks and blood from the right is directed into the pulmonary trunk. Initially the septum is composed only of endocardial cells but this is later supplemented by neural crest cells.