Hirschsprung Disease - Aganglionic Distal Colon

A 3-week-old male infant presents with delayed passage of meconium beyond 48 hours, chronic constipation requiring rectal stimulation, progressive abdominal distension, and failure to thrive. On examination, there is an empty rectum with explosive release of feces on withdrawal of the examining finger (blast sign). Contrast enema shows a cone-shaped transition zone with a narrow distal segment and dilated proximal colon. Rectal suction biopsy 3 cm above the dentate line shows absence of ganglion cells in both Meissner's and Auerbach's plexuses with increased acetylcholinesterase activity. The structure marked **C** in the diagram represents the narrow distal aganglionic segment. Which of the following best explains the pathophysiology of this segment's dysfunction?