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KMID : 0363719960290030235
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Korean Journal of Anatomy
1996 Volume.29 No. 3 p.235 ~ p.241
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Quantitative Synoptic Analysis of the Sacral Parasympathetic Neurons of the Rat
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Park Mae-Ja
Cho Hee-Jung
Song In-Hwan
Bae Yong-Chul
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Abstract
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Aim of the present study is to analyze the synaptic characteristics of the sacral parasympathetic preganglionic (SPP) neurons and define the microneural circuit of the sacral parasympathetic nucleus of the rat. RL-29, a kind of lectin, is known to be detected in the autonomic neurons in the spinal cord, dorsal root ganglion cells, was reported to be used as a marker for the parasympathetic preganglionic neurons in this study. RL-29 immunoreactive material is found densely in the cytoplasm and nucleus as a cytoplasmic soluble form and membrane bound form. RL-29 IR-SPP
neurons do not have synaptic structures, densely on their soma and dendrites. On the RL-29 IR-neurons, synaptic terminals containing spherical vesicles comprise 70% of the synaptic teminals. Synaptic terminals containing pleomorphic vesicle with dense cored vesicles comprise 16% and terminals containing elongated vesicles account for 11% of the total synaptic terminal population. Ratio of population density of each type of synaptic terminals is almost the same on RL-29 IR-soma and -dendrite. Asymmetrical synapsis are the most frequently observed on the RL-29 IR-dendrites, but on the RL-29 IR-soma, symmetrical synapsis are two times more than asymmetrical ones. It
suggests that inhibitory inputs are associated mostly with soma. Infrequently, RL-29 immunoreactive (IR) neurons make direct contacts with RL-29 IR synaptic terminals and RL-29 IR dendrites. These data suggest that RL-29 IR SPP neurons make direct synapsis with other RL-29 IR SPP neurons in the sacral parasympathetic nucleus
as well as primary afferents from the visceral organs. In conclusion, it gives morphological evidence that SPP neurons receive afferents inputs from four different sources, i.e., i) visceral afferents from pelvic organs, ii) interneurons in the parasympathetic preganglionic neurons, ⅲ) the other parasympathetic preganglionic neurons and, iv)
descending input from brain stem.
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KEYWORD
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RL-29, Lectin, Parasympathetic preganglionic neuron, Electron microscopic immumohistochemistry
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