Identification of distinct topographical distributions of lumbar sympathetic and sensory neurons projecting to end organs with different functions in the cat.

A comparison has been made between the lumbar sensory and sympathetic pre- and postganglionic neurons that project in the lumbar splanchnic nerves and those that project in the caudal lumbar sympathetic trunk of the cat. The neuron cell bodies have been labeled retrogradely with horseradish peroxidase applied to the central end of their cut axons near the inferior mesenteric ganglion on one side, and the results have been compared with those obtained after labeling the contralateral lumbar sympathetic trunk of the same animal (Jänig and McLachlan, '86). The numbers, segmental distribution, location, and size of the labeled somata have been determined quantitatively. The data for individual animals confirm in every way those previously reported for separate experiments in different groups of animals. In addition, similar experiments were performed in which the neurons projecting in the white rami of either L4 or L5 were labeled. This procedure labeled populations of neurons that overlapped both splanchnic and paravertebral populations. Consideration of the spatial distributions and numbers of sensory and preganglionic neurons with destinations in somatic and visceral domains has enabled us to describe the different topography of these neuron populations with respect to function.