The central projections of visceral primary afferent neurons of the inferior mesenteric plexus and hypogastric nerve and the location of the related sensory and preganglionic sympathetic cell bodies in the rat

• DOI: 10.1007/bf00315762
• Publication Date: 2004-10-12T14:14:54Z
• Authors: Winfried Neuhuber
• Keywords: Plexus; Lateral funiculus; Hypogastric nerve; Axoplasmic transport; Dorsal root ganglion

The central projections of visceral primary afferents of the inferior mesenteric plexus and hypogastric nerve of the rat were investigated using the transganglionic transport of horseradish peroxidase (HRP). In addition, the location of the corresponding spinal ganglion cells as well as the preganglionic sympathetic neurons is demonstrated. Labelled afferent axons were found in dorsal roots, dorsal root entry zone (preferentially in its lateral part), in all parts of the tract of Lissauer, and in the dorsolateral funiculus. Preterminal axons and/or terminals were distributed mainly to laminae I, IIa and the nucleus of the dorsolateral funiculus. Fewer afferents reached laminae IIb, III–V and X. Afferent projections are densest at L1 and 2 and the caudal T13, but extend up to T10 rostrally, and at least down to L4 caudally. A few visceral afferents ascend to the nucleus gracilis. The great majority of sensory and preganglionic sympathetic cell bodies is located at levels L1 and 2 bilaterally. A few cells are found in decreasing numbers rostrally up to T11. Preganglionic sympathetic neurons (PSN) are located in nucleus intermediolateralis (IML), n. intercalatus (IC) and n. commissuralis dorsalis (DCN). Axons of DCN and IC neurons run laterally, joining those of IML neurons on their way to the ventral roots. Dendrites of IML neurons ramify in all directions but preferentially to the dorsal horn and dorsolateral funiculus. Dendrites of IC and DCN neurons are distributed mainly mediolaterally, the latter also ventrally around the canalis centralis.