Innervation of individual guinea-pig superior cervical ganglion cells by axons with similar conduction velocities.

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Abstract
Individual neurons in the guinea-pig superior cervical ganglion were studied to determine whether they are innervated by preganglionic axons with similar conduction velocities. Latencies of synaptic responses recorded intracellularly in ganglion cells after stimulation of individual ventral roots varied from 28-430 ms. Most of this variability arose from differences in preganglionic conduction velocity. The 12 different axons that on average innervate each ganglion cell tended to have broadly similar conduction velocities; a neuron receiving a rapidly conducting input was usually contacted by other rapidly conducting axons, and vice versa. Preferential innervation of individual neurons by axons with similar conduction velocities were evident even when only axons arising from the same spinal segment were compared. Preferential innervation by axons of similar conduction velocity cannot be simply a manifestation of segmental preferences. The mature pattern of innervation in mammalian sympathetic ganglia may reflect the functional as well as the positional qualities of the synaptic partners.