NBME Form 16 Practice Test

Neural crest cells are the population that forms the aorticopulmonary septum. As the heart outflow tract develops, neural crest cells migrate into the truncus arteriosus and bulbus cordis to create the conotruncal ridges, which spiral and fuse to divide the single truncus into the aorta and pulmonary artery. When this neural crest–driven septation fails, you get persistent truncus arteriosus with a single arterial trunk often associated with a ventricular septal defect.

Other cell types listed don’t drive this specific septation: myoblasts contribute to cardiac muscle, endothelial cells line vessels, and mesenchymal stem cells are multipotent but aren’t the source of the conotruncal septum formation that separates the great arteries.