[The ultrastructure of Electrophorus electricus spinal electromotoneurons, with or without acetylcholinesterase activity].

The acetylcholinesterase-rich neurons existing in the electromotor nucleus (EMN or "CMD") of the spinal cord of the Electrophorus electricus exhibit the presence of numerous chemical synapses on their surfaces, whereas the neurons without enzymatic activity which occupy the major part of the grey matter of the EMN are characterized by electrical synapses.