Morphology and projections of neurons in Remak's nerve of the domestic fowl revealed by intracellular injection of biocytin.
Micro-injections of biocytin were made into neurons in whole-mount preparations of Remak's nerve of the domestic fowl to visualise the morphology and projections of Remak's neurons. Remak's neurons were classified into four distinct morphological types. Remak type-I and -II neurons had a morphology resembling that of mammalian sympathetic neurons. Type-I neurons (found only in juxta-jejunal ganglia) had numerous primary dendritic processes (8-14) with large dendritic fields and extensive dendritic arborizations. Type-II neurons had 2-9 primary dendritic processes, large dendritic fields and sparse dendritic branching. These were found in similar numbers in juxta-rectal and juxta-jejunal ganglia. Remak type-III neurons were the most numerous cell type of juxta-rectal ganglia. They had small cell somata and short dendritic processes that branched infrequently. Remak type-IV neurons (found only in juxta-jejunal ganglia) had a morphology resembling that of invertebrate neurons in that they possessed a prominent long tapering axon from which most of the numerous long dendritic processes emerged. In juxta-jejunal ganglia, all type-IV and most type-I, -II and -III neurons projected orally, whereas axons of juxta-rectal neurons (types II and III) projected either orally or aborally, or projected directly into a lateral nerve bundle supplying the gut. These regional differences in neuron types and axonal projections suggest that different neural circuits exist between Remak's nerve and the small and large intestine.
Lunam
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Department of Internal Medicine and Physiology, University of Virginia Health Sciences Center, Charlottesville 22902, USA.
Smith
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TK
D000818:Animals; D001369:Axons; D048429:Cell Size; D002645:Chickens / Q000033:anatomy & histology*; D003712:Dendrites; D005260:Female; D005725:Ganglia, Autonomic / Q000166:cytology; D007422:Intestines / Q000294:innervation; D007583:Jejunum / Q000294:innervation*; D008239:Lysine / Q000031:analogs & derivatives*; D008297:Male; D008845:Microinjections; D009474:Neurons / Q000166:cytology* / Q000648:ultrastructure; D012007:Rectum / Q000294:innervation*
C013411:biocytin; D008239:Lysine