Journal of Neuroscience, Vol 4, 1-12, Copyright © 1984 by Society for Neuroscience
Regional innervation of rabbit ciliary ganglion cells by the terminals of preganglionic axons
CJ Forehand and D Purves
In the rabbit, ciliary ganglion neurons with dendrites maintain inputs from
several different axons during the period of synaptic rearrangement that
occurs in early postnatal life. Neurons without dendrites, on the other
hand, lose the majority of their initial inputs and are innervated in
maturity by the terminals of only one or two axons (Purves, D., and R.I.
Hume (1981) J. Neurosci. 1: 441-452; Hume, R.I., and D. Purves (1981)
Nature 293: 469-471). We have explored the basis of this phenomenon by
individually marking preganglionic axons and the neurons they innervate
with horseradish peroxidase. In general, the innervation of geometrically
complex (multiply innervated) neurons by individual preganglionic axons is
regional. That is, the synaptic contacts made by an axon on these neurons
are limited to a portion of the postsynaptic surface that includes some,
but not all, of the dendrites. This regional innervation of target neurons
is consistent with the view that dendrites allow multiple innervation to
persist by providing relatively separate postsynaptic domains for
individual preganglionic axons. Such regional innervation may mitigate
competitive interactions between the several axons which initially
innervate the same neuron.