Development of the submucous plexus in the large intestine of the mouse

In the small intestine of both embryonic birds and mammals, neuron precurso rs aggregrate first at the site of the myenteric plexus, and the submucous plexus develops later. However, in the large intestine of birds, the submuc osal region is colonised by neural-crest-derived cells before the myenteric region (Burns and Le Douarin, Development 125:4335-4347, 1998). Using anti sera that recognize undifferentiated neural-crest-derived cells (p75(NTR)) and differentiated neurons (PGP9.5), we examined the colonisation of the mu rine large intestine by neural-crest-derived cells and the development of t he myenteric and submucosal plexuses. At E12.5, when the neural crest cells were migrating through and colonising the hindgut, the hindgut mesenchyme was largely undifferentiated, and a circular muscle layer could not be disc erned. Neural-crest-derived cells migrated through, and settled in, the out er half of the mesenchyme. By E14.5, neural-crest-derived cells had colonis ed the entire hindgut; at this stage the circular muscle layer had started to differentiate. From E14.5 to E16.5, p75(NTR-) and PGP9.5-positive cells were observed on the serosal side of the circular muscle, in the myenteric region, but not in the submucosal region. Scattered, single neurons were fi rst observed in the submucosal region around E18.5, and groups of neurons f orming ganglia were not observed until after birth. The development of the enteric plexuses in the murine large intestine therefore differs from that in the avian large intestine.