Sacral Neural Crest Cells Colonise Aganglionic Hindgut in Vivo but Fail to Compensate for Lack of Enteric Ganglia

Abstract

The vagal neural crest is the origin of majority of neurons and glia that constitute the enteric nervous system, the intrinsic innervation of the gut. We have recently confirmed that a second region of the neuraxis, the sacral neural crest, also contributes to the enteric neuronal and glial populations of both the myenteric and the submucosal plexuses in the chick, caudal to the level of the umbilicus. Results from this previous study showed that sacral neural crest-derived precursors colonised the gut in significant numbers only 4 days after vagal-derived cells had completed their migration along the entire length of the gut. This observation suggested that in order to migrate into the hindgut and differentiate into enteric neurons and glia, sacral neural crest cells may require an interaction with vagal-derived cells or with factors or signalling molecules released by them or their progeny. This interdependence may also explain the inability of sacral neural crest cells to compensate for the lack of ganglia in the terminal hindgut of Hirschsprung's disease in humans or aganglionic megacolon in animals. To investigate the possible interrelationship between sacral and vagal-derived neural crest cells within the hindgut, we mapped the contribution of various vagal neural crest regions to the gut and then ablated appropriate sections of chick vagal neural crest to interrupt the migration of enteric nervous system precursor cells and thus create an aganglionic hindgut model in vivo. In these same ablated animals, the sacral level neural axis was removed and replaced with the equivalent tissue from quail embryos, thus enabling us to document, using cell-specific antibodies, the migration and differentiation of sacral crest-derived cells. Results showed that the vagal neural crest contributed precursors to the enteric nervous system in a regionalised manner. When quail-chick grafts of the neural tube adjacent to somites 1-2 were performed, neural crest cells were found in enteric ganglia throughout the preumbilical gut. These cells were most numerous in the esophagus, sparse in the preumbilical intestine, and absent in the postumbilical gut. When similar grafts adjacent to somites 3-5 or 3-6 were carried out, crest cells were found within enteric ganglia along the entire gut, from the proximal esophagus to the distal colon. Vagal neural crest grafts adjacent to somites 6-7 showed that crest cells from this region were distributed along a caudal-rostral gradient, being most numerous in the hindgut, less so in the intestine, and absent in the proximal foregut. In order to generate aneural hindgut in vivo, it was necessary to ablate the vagal neural crest adjacent to somites 3-6, prior to the 13-somite stage of development. When such ablations were performed, the hindgut, and in some cases also the cecal region, lacked enteric ganglionated plexuses. Sacral neural crest grafting in these vagal neural crest ablated chicks showed that sacral cells migrated along normal, previously described hindgut pathways and formed isola...

Bone morphogenetic protein signaling pathway plays multiple roles during gastrointestinal tract development

“…The neural tube caudal to somite pair 28 provides neural crest cells that colonize only the postumbilical gut (mid-midgut to anus/cloaca). This sacral neural crest colonizes the post-umbilical gut in a caudocranial direction (Burns et al, 2000;Hearn and Newgreen, 2000;Kapur, 2000). After colonization, the ENS is patterned in two concentric rings of ganglia within the radial axis of the gut.…”

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

“…Subsequent analysis of the developing gut for the presence of quail cells within the enteric plexuses allowed the origin of ENS cells to be defined to the vagal region of the neural crest, adjacent to somites 1-7, which populates the entire length of the gut, while a second region of the neuraxis, the sacral neural crest, caudal to the 28 th pair of somites, was also shown to contribute cells to the hindgut (Le Douarin andTeillet, 1973, Le Douarin andTeillet, 1974). Although numerous authors have subsequently supported the data concerning the contribution of the vagal NC (Burns et al, 2000, Durbec et al, 1996, Epstein et al, 1994, due to conflicting findings, the precise role of the sacral neural crest in ENS formation remained controversial for many years. Evidence supporting a role for sacral NCC in ENS development came from cell labelling studies that traced the development of sacral NCC in the chick using a monoclonal antibody (NC-1) that binds to migrating NCC (Pomeranz and Gershon, 1990).…”

“…These problems were overcome in a series of more recent studies initiated in the laboratory of Nicole Le Douarin, utilising quail-chick interspecies grafting to selectively label sub-populations of NCC, in conjunction with antibody doublelabelling to identify quail cells and neuronal and glial phenotypes within chick enteric ganglia. The combination of these techniques allowed the spatiotemporal migration pathways of vagal and sacral NCC to be determined, along with the identification of the subsequent phenotypes of crest-derived cells within the gut (Burns et al, 2000, Burns andLe Douarin, 1998;Burns and Le Douarin, 2001). These studies demonstrated that vagal NCC initially accumulated in the caudal branchial arches, then entered the foregut mesenchyme at E3 and migrated in a rostro-caudal direction, colonising the hindgut during E7-9.…”

Toward a better understanding of enteric gliogenesis

“…14 This cell population is divided into several subpopulations depending of their origin along the anterior-posterior axis of the neural tube: cranial, cardiac, vagal, trunk and sacral. The vast majority of ENS progenitors (also refer to as enteric NCCs) has a vagal origin, 14 although minor contingents are also provided by the sacral region 15 and by NCC-derived Schwann cell precursors within the extrinsic nerves of the developing bowel. 16 In the mouse, enteric NCCs of vagal origin initially colonize the foregut mesenchyme around embryonic day (E) 9.5 and then migrate in the rostrocaudal direction to reach the end of the hindgut by E14.5.…”