Congenital megacolon develops secondary to failure of -: (A) Migration of vagal neural crest cells to gut, (B) Neurogenesis, (C) Defecation reflex, (D) External anal sphincter relaxation
Answer is A. Ans. is 'a' i.e., Migration of vagal neural crest cells to gut * Hirschsprung's disease (congenital megacolon) is characterised by the congenital absence of intramural ganglion cells (aganglionosis) and the presence of hypertrophic nerves in the distal large bowel.* The absence of ganglion cells is due to a failure of migration of vagal neural crest cells into the developing gut.* The affected gut is in spasm causing a functional bowel obstruction.