Distribution of splenic, mesenteric and renal neurons in sympathetic ganglia in rats.

The distribution of postganglionic neurons innervating the spleen, intestine and kidney in paravertebral and prevertebral sympathetic ganglia was studied in rats using retrograde transport of fluorescent dyes. Labelled cells were counted in the thoracolumbar chain ganglia T6-L4, splanchnic ganglia and the solar plexus (fusion of left and right coeliac ganglia and superior mesenteric ganglion). Most splenic neurons were located in the splanchnic ganglion (64%), mesenteric neurons in the solar plexus (96%) and renal neurons in the sympathetic chain ganglia (80%). These three groups of neurons were distributed in overlapping ganglia within the paravertebral chain. Innervation of the spleen and intestine from the chain ganglia was bilateral, whereas innervation of the kidney was almost entirely ipsilateral. In conclusion, the sympathetic postganglionic neurons controlling the spleen, intestine and kidney have their cell bodies in different ganglia. These three groups of neurons are candidates for innervation by different subgroups of preganglionic neurons.