Migration of neural crest-derived enteric nervous system precursor cells to and within the gastrointestinal tract.

The enteric nervous system, the intrinsic innervation of the gastrointestinal tract, consists of large numbers of phenotypically diverse neurons and glial cells, arranged in complex interconnecting plexuses situated between the smooth muscle layers of the gut wall. Recently, the enteric nervous system has attracted much attention from developmental biologists whose efforts have focused on analysing the cellular origins of enteric nervous system precursor cells, how these cells migrate to and within the gut and the identification of signalling mechanisms which cause migrating cells to differentiate into the appropriate phenotypes in the appropriate locations. This review summarises the state of knowledge concerning the early stages of enteric nervous system development and concentrates on: (i) the embryological origins of the neural crest cells which colonise the gastrointestinal tract, (ii) their spatiotemporal migration within the gut, (iii) the possible pre-specification of neural crest cells as enteric nervous system precursors and (iv) factors influencing their directional migration within the gut.