The electromotor system of the electric eel investigated with horseradish peroxidase as a retrograde tracer

Michael V.L. Bennett, Clara Sandri

Research output: Contribution to journalArticle

4 Scopus citations


The electromotor system of the electric eel, Electrophorus electricus, was studied by injection of horseradish peroxidase as a retrograde tracer. The electromotor neurons, which innervate the electrocytes, comprise a midline nucleus, largely dorsal to the spinal canal. Spinal motoneurons lie ventrolaterally. The electromotor and skeletal motor neuron populations correspond to the acetylcholinesterase-negative and -positive cells previously described. The medullary relay neurons were labeled following HRP injection into the spinal cord at a level where electromotor neurons occurred, but not after injection into the cord in the abdominal region rostral to these cells. Other medullary neurons, presumably bullospinal motor fibers, were labeled after both levels of spinal cord injection. The results suggest that these axosomatic synapses, which are electrically transmitting but morphologically mixed, take up retrograde tracers in a manner similar to chemical synapses and that tracer uptake is at least largely at terminal regions.

Original languageEnglish (US)
Pages (from-to)22-30
Number of pages9
JournalBrain Research
Issue number1-2
StatePublished - May 29 1989



  • Electric eel
  • Electric organ
  • Electrical synapse
  • Horseradish peroxidase
  • Morphologically mixed synapse
  • Retrograde axonal transport

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology

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