Comparison of the distributions of renal and splenic neurons in sympathetic ganglia

Abstract

Postganglionic neurons in different sympathetic ganglia are innervated selectively by preganglionic neurons originating from different segments of the spinal cord. These selective connections between pre- and postganglionic neurons may determine the specificity with which postganglionic nerves participate in differential reflex reactions. Because specificity of renal and splenic nerve responses to stimulation of visceral afferent nerves may depend on the distribution of postganglionic neurons in sympathetic ganglia, retrograde axonal transport of horseradish peroxidase was employed in this study to identify the ganglionic distribution of cell bodies of postganglionic neurons supplying the kidney and spleen in cats. Superior mesenteric, left and right celiac ganglia usually are fused together into a complex ganglion (solar plexus) in the cat. Most labeled cell bodies of renal nerves were clustered in groups within the solar plexus, but some cell bodies of renal neurons were observed in upper lumbar (L1–L3) and lower thoracic (T12–T13) paravertebral sympathetic ganglia. In contrast, 90% of labeled splenic neurons were scattered randomly throughout the left and right celiac poles of the solar plexus. In conclusion, the disparate distribution of renal and splenic neurons in sympathetic ganglia provides an anatomical basis for differential reflex responses in the two populations of nerves.