Persistent truncus arteriosus results from failure of which embryological process?

• A Failure of the aorticopulmonary septum to spiral and partition the truncus arteriosus
• B Failure of the endocardial cushions to fuse
• C Failure of the interventricular septum to close the membranous portion
• D Abnormal migration of neural crest cells to the outflow tract ✓

Explanation

Persistent truncus arteriosus occurs when the truncal/bulbar ridges (which contain neural crest cell derivatives) fail to form the aorticopulmonary septum that normally divides the truncus arteriosus into the aorta and pulmonary trunk. Neural crest cells from the hindbrain migrate into the pharyngeal arches and outflow tract of the heart; their failure to populate the truncal ridges leads to a single arterial vessel arising from both ventricles. Answer A is mechanistically a consequence but the primary cellular failure is neural crest migration, making D the more precise answer per current embryology.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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