Journal of Neuroscience, Vol 6, 3459-3464, Copyright © 1986 by Society for Neuroscience
Specific innervation of neurons in the paravertebral sympathetic ganglia of the chick
JW Yip
I have explored the chick sympathetic system as a model for the study of
specific synapse formation by examining the pattern of ganglion cell
innervation by preganglionic axons in 2 different ganglia. Using
intracellular recording and HRP labeling techniques, the innervation of the
12th and 15th cervical ganglia (C12 and C15) was examined. Sympathetic
ganglion cells of the chick are innervated in a stereotyped manner by
preganglionic axons arising from different levels of the spinal cord. While
each ganglion is innervated by preganglionic axons arising from several
spinal cord segments, individual ganglion cells are innervated by only some
of the spinal segments that supply each ganglion as a whole. The subset of
spinal segments is always contiguous, with 1 segment providing the dominant
innervation to the cell. Spinal segments adjacent to the dominant segment
provide synaptic inputs that diminish as a function of distance from the
dominant segment. This pattern of ganglion cell innervation in the chick is
similar to that of the mammal, where re-innervation studies have suggested
that ganglion cell innervation is selective. The similarity in the
innervation of avian and mammalian sympathetic neurons suggests that the
rules that underlie the specificity of synapse formation in the sympathetic
system of the 2 species are the same. Because of the accessibility of the
chick embryo for experimental manipulations during development, it is now
possible to study the cellular basis that underlies the specificity of
synapse formation in this relatively simple nervous system.