Visceral afferent and efferent columns in the spinal cord of the teleost, Ictalurus punctatus.
In tetrapod vertebrates, neural circuitries subserving visceral and somatic reflexes are each represented in distinct columns of cells within the gray area of the spinal cord. To determine the location of visceral elements of the spinal cord of a teleost fish, crystals of the carbocyanine dye 1,1'dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine (DiI), were placed on either the abdominal sympathetic (mesenteric) nerves, the coeliac ganglia, or on the rostral three somatic spinal nerves, in fixed specimens of the channel catfish, Ictalurus punctatus. In fish in which DiI had been placed on the mesenteric nerves, labeled fibers coursed along the lateral margin of the dorsal horn within the first and second spinal segments, and appeared to terminate in a region at the base of the dorsal horn. In contrast, when DiI crystals were placed on the somatic spinal nerves, labeled primary afferents terminated in the dorsalmost two thirds of the dorsal horn, as well as in ventral and ventromedial areas of the medial funicular nuclear complex. Labeled somata (motor neurons) were situated in the ventral horn. When DiI crystals were placed bilaterally on the coeliac ganglia, labeled piriform and fusiform preganglionic neurons occurred in intermediate positions adjacent to the central canal, corresponding to the paracentral nucleus of Herrick, and in the lateral funiculus. These results demonstrate that somatic and visceral afferent and efferent functional columns are distinct in a teleost fish as they are in amniote vertebrates.
Goehler
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Department of Cellular and Structural Biology, University of Colorado Health Sciences Center, Denver 80262, USA.
Finger
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D000818:Animals; D001339:Autonomic Fibers, Preganglionic / Q000166:cytology; D002232:Carbocyanines; D004525:Efferent Pathways / Q000033:anatomy & histology; D005456:Fluorescent Dyes; D005727:Ganglia, Spinal / Q000648:ultrastructure; D005728:Ganglia, Sympathetic / Q000166:cytology; D007059:Ictaluridae / Q000033:anatomy & histology*; D008643:Mesentery / Q000294:innervation; D009411:Nerve Endings / Q000648:ultrastructure*; D013116:Spinal Cord / Q000033:anatomy & histology*; D013153:Splanchnic Nerves / Q000648:ultrastructure; D009626:Terminology as Topic; D014781:Viscera / Q000294:innervation*
D002232:Carbocyanines; D005456:Fluorescent Dyes; C024286:3,3'-dioctadecylindocarbocyanine