Journal of Neuroscience, Vol 4, 2434-2444, Copyright © 1984 by Society for Neuroscience
Dorsal root ganglia development in chicks following partial ablation of the neural crest
VM Carr
To assess the effects of reduced competition for peripheral targets on
developing brachial dorsal root ganglia (DRG), chick embryos were subjected
to partial ablations of the brachial neural crest at stages 13 or 14
(Hamburger, V., and H.L. Hamilton (1951) J. Morphol. 88: 49- 92), using an
ophthalmological cauterization unit. In the initial studies reported here,
ganglia developing from the remaining crest material were examined for
ganglionic volume and neuronal size, neuronal number, and degenerative
activity at stage 35. Results showed that the lesion procedure resulted in
the reduction or absence of one or two ganglia on each side at the level of
DRG 15 to DRG 17. Hypertrophies occurred in other ganglia remaining at
these and at more rostral levels and ranged up to 220%. These hypertrophies
were most pronounced, however, not in the ganglia adjacent to those
lesioned but rather in more remote ganglia, including those at cervical
levels. Accompanying these ganglionic changes were significant alterations
in all three neuronal parameters examined. The findings clearly demonstrate
a responsiveness of chick brachial DRG to reduced competition resulting
from neural crest ablations and that such responsiveness occurs along
several axial segments.