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Chemically distinct preganglionic inputs to iris-projecting postganglionic neurons in the rat: A light and electron
I Grkovic1, S L Edwards, S M Murphy
1Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria 3052, Australia. i.grkovic@anatomy.unimelb.edu.au
The Journal of Comparative Neurology
|August 28, 1999
Summary
Pericellular baskets of preganglionic terminals in autonomic ganglia primarily target the central neuron
Area of Science:
- Neuroscience
- Autonomic Nervous System Research
- Cellular Neuroscience
Background:
- Autonomic postganglionic neurons are ensheathed by preganglionic terminal baskets.
- Light microscopy assumes these baskets target the central neuron, enabling connectivity studies.
- Uncertainty exists if baskets also innervate surrounding neurons' dendrites.
Purpose of the Study:
- To ultrastructurally determine the precise target of preganglionic pericellular baskets.
- To investigate basket innervation in a context with functionally diverse surrounding neurons.
- To validate light microscopy assumptions in autonomic ganglia.
Main Methods:
- Serial section electron microscopy of rat superior cervical ganglion.
- Retrograde tracing to identify iris-projecting postganglionic neurons.
- Immunohistochemistry for calcitonin gene-related peptide (CGRP) in preganglionic terminals.
Main Results:
- Iris-projecting neurons were identified as single cells.
- Preganglionic terminals containing CGRP formed pericellular baskets around these neurons.
- Ultrastructural analysis confirmed baskets exclusively innervated the soma of the central neuron, not surrounding dendrites.
Conclusions:
- Preganglionic pericellular baskets in the superior cervical ganglion target the soma of the central neuron.
- This finding supports the reliability of light microscopy for mapping preganglionic neuron connectivity.
- Autonomic ganglia exhibit specific targeting of preganglionic inputs to postganglionic somata.