Circuits and projections of cat stellate ganglion.
BACKGROUND
Although connections of stellate ganglion (SG) have been widely explored, some features of pathways and projections remain unknown, such as the source and fate of preganglionic axons present in output branches, including both synaptically interrupted and traversing pathways as well as axon composition (efferent and afferent) of these output nerves.


METHODS
Circuits and central projections of cat SG were investigated using horseradish peroxidase (HRP) tracer and electrophysiologic techniques including stimulation of ganglionic branches during recording of genesis of compound action potentials in other nerves or centrally evoked responses.


RESULTS
All branches of SG including vertebral nerve are mixed, i.e., they contain axons that synapse in the periphery or traverse ganglia. A novel synaptically interrupted pathway bi-directionally coursing along subclavian branches and inferior cardiac nerve was identified. Preganglionic axons traversing stellate ganglion course in communicating branch to vagus nerve and to inferior cardiac nerve, a small number of these preganglionic axons traversing stellate ganglion reach cervical sympathetic trunk via subclavian branches. For the first time, a small number of preganglionic traversing pathways were also detected in vertebral nerve. Afferent axons with somata located in C8-T7 dorsal root ganglia, identified in all branches of SG, projected centrally to neurons in thalamus and somatosensory zones of cerebral cortex and coincided with afferent projections of brachial plexus.


CONCLUSIONS
Present data contribute to the morphologic description of autonomic regulation of thoracic organs, including centrally independent peripheral autonomic axon reflexes.
Nozdrachev
Alexander D
AD
Department of Physiology, St. Petersburg State University, St. Petersburg, Russia.
Fateev
Mikhail M
MM
Jiménez
Beatriz
B
Morales
Miguel A
MA
D000818:Animals; D001369:Axons / Q000378:metabolism*; D002415:Cats; D004594:Electrophysiology; D005260:Female; D006863:Hydrogen-Ion Concentration; D008297:Male; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism*; D009475:Neurons, Afferent / Q000378:metabolism; D013116:Spinal Cord / Q000166:cytology; D013233:Stellate Ganglion / Q000033:anatomy & histology* / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000166:cytology; D013788:Thalamus / Q000502:physiology