Persistent truncus arteriosus results from failure of which developmental process?
- A Fusion of the endocardial cushions to close the AV canal
- B Formation of the sinus venosus valves
- C Neural crest cell migration and spiral septation of the truncus arteriosus by the aorticopulmonary septum ✓
- D Looping of the heart tube to the right (dextrocardia)
Explanation
The truncus arteriosus (common outflow tract) is divided into the ascending aorta and pulmonary trunk by the aorticopulmonary septum, which grows in a spiral pattern. This spiral septation depends critically on neural crest cells migrating from the dorsal neural tube into the cardiac outflow tract. Failure of neural crest migration and septation results in persistent truncus arteriosus (a single arterial vessel arising from both ventricles). The same neural crest migration deficiency underlies DiGeorge syndrome. Endocardial cushion fusion defects cause AV septal defects. Heart looping defects cause dextrocardia.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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