Congenital megacolon develops secondary to failure of -

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.