Fine scale differences within the vagal neural crest for enteric nervous system formation

• Published in: Developmental biology 2019-02, Vol.446 (1), p.22-33
• Main Authors: Simkin, Johanna E., Zhang, Dongcheng, Stamp, Lincon A., Newgreen, Donald F.
• Format: Article
• Language: English
• Subjects: Avian embryo; Cell fate; Enteric nervous system; Neural crest; Somite-levels; Vagal level
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2018.11.007

The enteric nervous system is mostly derived from vagal neural crest (NC) cells adjacent to somites (s)1–7. We used in ovo focal fluorescent vital dyes and focal electroporation of fluorophore-encoding plasmids in quail embryos to investigate NC cell migration to the foregut initially and later throughout the entire gut. NC cells of different somite-level origins were largely separate until reaching the foregut at about QE2.5, when all routes converged. By QE3.5, NC cells of different somite-levels became mixed, although s1-s2 NC cells were mainly confined to rostral foregut. Mid-vagal NC-derived cells (s3 and s4 level) arrived earliest at the foregut, and occurred in greatest number. By QE6.5 ENS was present from foregut to hindgut. Mid-vagal NC-derived cells occurred in greatest numbers from foregut to distal hindgut. NC-derived cells of s2, s5, and s6 levels were fewer and were widely distributed but were never observed in the distal hindgut. Rostro-vagal (s1) and caudo-vagal (s7) levels were few and restricted to the foregut. Single somite levels of quail neural tube/NC from s1 to s8 were combined with chick aneural ChE4.5 midgut and hindgut and the ensemble was grown on the chorio-allantoic membrane for 6 days. This tests ENS-forming competence in the absence of intra-segmental competition between NC cells, of differential influences of segmental paraxial tissues, and of positional advantage. All vagal NC-levels, but not s8 level, furnished enteric plexuses in the recipient gut, but the density of both ENS cells in total and neurons was highest from mid-vagal level donors, as was the length colonised. We conclude that the fate and competence for ENS formation of vagal NC sub-levels is not uniform over the vagal level but is biased to favour mid-vagal levels. Overviewing this and prior studies suggests the vagal region is, as in its traditional sense, a natural unit but with complex sub-divisions. •Neural crest cells of somite level s2 to s6 are fated to contribute to the ENS throughout the gut of avian embryos.•Neural crest cells of s3 and s4 levels have the most extensive and numerically largest contribution to the ENS.•Neural crest cells of somite levels s1 and s7 contribute ENS only to the foregut.•The capability of isolated somite levels of neural crest to form ENS in experiments exactly parallels the fate pattern.•The vagal neural crest level with somites s1 to s7 is a natural unit with complex axial pre-specification.