Cholinergic differentiation of presumptive adrenergic neuroblasts in interspecific chimeras after heterotopic transplantations.

Abstract

The levels of the neural axis from which parasympathetic and orthosympathetic neurons and adrenomedullary cells are derived under normal developmental conditions were determined in avian embryos by a biological labeling technique. The technique is based on nuclear differences between two species of birds, the chick and the quail. In quail interphase nuclei a part of the chromatin is condensed in large heterochromatic masses associated with nucleolus, while in the chick, DNA is evenly dispersed in the nucleoplasm. These characteristics provide a stable nuclear marker that can be used to study cell migrations and differentiation in chimeric embryos resulting from the association of quail and chick tissues. Isotopic and heterotopic transplantations of quail neural primordium into chick before the outset of neural crest cell migration show that the autonomic ortho- and parasympathetic neuroblasts are not determined to differentiate into cholinergic or adrenergic neurons when they begin to migrate. The neurotransmitter synthesized by crest autonomic neuroblasts depends on the microenvironment in which crest cells become localized at the term of their migration. The splanchnic mesoderm induces presumptive adrenergic cells to become fully differentiated cholinergic neurons.

Critical numbers of neural crest cells are required in the pathways from the neural tube to the foregut to ensure complete enteric nervous system formation

“…By contrast, trunk NCC were never observed within the gut upon grafting of a single somite length of trunk neural tube into 3-6 ablated embryos; these cells migrated away from the neural tube and contributed to the vagus nerves. The data for trunk NCC failing to colonise the gut are in contrast to the previous findings of Le Douarin and colleagues (Le Douarin et al, 1975;Le Douarin and Teillet, 1974), who described trunk NCC within the gut following the grafting of the trunk neural tube into the vagal region. It is possible that we did not see quail trunk NCC in guts of 3-6 ablated embryos because we did not replace the entire vagal neural tube with trunk, as carried out by the authors of this previous work (Le Douarin et al, 1975;Le Douarin and Teillet, 1974).…”

Dissimilar regulation of cell differentiation in mesencephalic (cranial)and sacral (trunk) neural crest cells in vitro

“…Differences in the fate of neural crest produced at different rostrocaudal levels are, to a certain extent, also based on the different microenvironments they encounter during their migration. Hence, while cholinergic parasympathetic ganglia are produced by the neural crest of the neck and the adrenergic sympathetic ganglia are produced by neural crest of the thorax, these specificities are reversed in reciprocal experiments where one population of neural crest is exposed to the microenvironment normally seen by the other (Le Douarin et al, 1975).…”

The Development of Developmental Neuroscience

“…The elegant and precise experiments of Nicole Le Douarin in the 70s on the influence of position on the outcome of transplanted neural crest cells (Le Douarin et al, 1975), and the culture experiments by Storey Landis and Paul Patterson on the factors that influence a cell to express noradrenergic or cholinergic neurotransmitters (Wolinsky et al, 1985) set the stage for thinking that the identity of a cell was in many ways scripted but malleable.…”