Segmental organization of sympathetic preganglionic neurons in the mammalian spinal cord.

We have used retrograde transport of horseradish peroxidase to determine the distribution of the preganglionic cell bodies whose axons join particular rami of the thoracic spinal cord in a series of guinea pigs, and in a small number of hamsters and cats. In contrast to other recent studies, our results show that the neurons sending axons to a ramus are confined to a single segment at the corresponding spinal level. This segmental organization supports the idea that the rostro-caudal position of preganglionic cell bodies is one determinant of selective synapse formation between preganglionic axons and sympathetic ganglion cells.