The proximal segment of the embryonic outflow (conus) does not participate in aortic vestibule development.

The posterior conus is an erroneous concept. The conal myocardium is reorganized in the free wall of the RV. Internally, the conal lumen is transformed into the pulmonary infundibulum. The aortic vestibule is formed from the ventro-superior cushion of the AV canal. Thus, the ventricular outflow tracts have different embryonic origins.