An Experimental Study on the Sympathetic Neuron Chains Using the Fluorescence Method for Biogenic Monoamines

Abstract

The arrangement of the neuron chains was studied by the fluorescence histochemical method of FALCK and HILLARP, to elucidate the distribution of monoamine containing nerve cells and the connection between nerve fibers in the sympathetic nervous system of the dog. Communicating rami and thoracic greater splanchnic nerve which center in the 13th thoracic ganglion, prevertebral ganglia, colonic nerve and intramural ganglia were subjected to observation. Section of nerves at various levels and administration of drugs affecting the metabolism of monoamines (reserpine and nialamide) were performed in addition to normal controls. The results obtained were as follows.
1. Monoaminergic fibers are not contained in the white communicating rami.
2. Non-monoaminergic nerve cells are found singly or in groups among fluorescent ones in both the para- and prevertebral ganglia (splanchnic and inferior mesenteric ganglia). Especially, they group in a definite region of the 13th thoracic ganglion where the white communicating rami penetrate.
3. Efferent monoaminergic nerve fibers are contained in the gray communicating rami, splanchnic and colonic nerve.
4. Monoaminergic nerve terminals are found around monoaminergic and nonmonoaminergic nerve cell bodies in both the para- and prevertebral ganglia.
5. There are two types of monoaminergic postganglionic fibers, namely short and long ones. The short axons terminate in the same ganglion where its own mother cell body is located, while long ones in a distant ganglion or intramural ganglia.
6. Nerve cells are non-fluorescent in the intramural ganglia of both Auerbach's and Meissner's plexuses.
From the above-described results ten defferent pathways, including five main and five subsidary ones, were proposed for the arrangement of the neuron chain from the lateral horn of spinal cord to the intestinal wall.