MIGRATION OF ENTERIC NEURAL CREST CELLS IN RELATION TO GROWTH OF THE GUT IN AVIAN EMBRYOS

Neural crest cell migration in the gut and the growth of the mid- and hindgut of avian embryos was investigated by a combination of whole-mo unt immunofluorescence of the HNK-1 neural crest marker epitope, chori oallantoic membrane grafting and morphometry. HNK-1-labelled cells adv anced rostrocaudally in the gut of quail embryos (to the duodenum by s tage HH 21, to the umbilicus by HH 25, to the ceca by HH 27, to the cl oaca by HH 33). The timetable in chick embryos appeared to be slightly slower, but neural cells were obscured by background fluorescence in this species. More rostral regions of the gut commenced rapid growth e arlier than more caudal regions (preumbilical small intestine after HH 26, postumbilical small intestine after HH 27 and colorectum after HH 28), and the small intestine and ceca grew most rapidly in length whi le the colorectum grew most rapidly in diameter, The rates of growth o f the gut were low prior to the stage when HNK-1-labelled cells normal ly arrive in the small intestine, ceca and rostral colorectum, but inc reased dramatically after arrival. In the caudal colorectum rapid grow th had commenced at the time of arrival of these cells. These data are consistent with the idea that a delay in arrival of vagal neural cres t cells at any point in the intestine could jeopardize the ability of the cells to fully populate the remainder of the gut, due to the norma l growth spurt causing the migration end-point to recede faster than t he rate of neural crest cell migration, Thus, a mismatch in timing of neural crest cell migration and gut growth could play a role in the et iology of some forms of Hirschsprung's disease.