Axon collaterals indicate broad intraspinal role for sacral preganglionic neurons.

The classic view of preganglionic neurons in spinal autonomic nuclei is that they convey information exclusively from the central nervous system to autonomic neurons in peripheral ganglia. The present morphological study in the cat sacral spinal cord demonstrates that these neurons may also make abundant synaptic connections within the spinal cord. Neurons labeled intracellularly with neurobiotin or horseradish peroxidase exhibited an expansive distribution of axon collaterals in spinal cord laminae I, V, VII, VIII, IX, X, and the ventrolateral funiculi. This broad-ranging axon-collateral system, which has the potential for multiple neuronal contacts, indicates widespread integrative functions for sacral preganglionic neurons within the spinal cord, in addition to functions currently known in the periphery.