Fine structure of the tuberous electroreceptor of the high-frequency electric fish, Sternarchus albifrons (gymnotiformes).

Sternarchus emits low voltage biphasic pulses at about 700-900/s. These signals (and changes in them caused by external objects) are detected by the tuberous or phasic electroreceptors. We used electron microscopy to examine extracellular compartments in the current pathway to the receptor cells, which are delineated by cells joined by tight junctions. Highly specialized accessory cells were found to separate the receptor cells from the extracellular space continuous with the exterior. Except for synaptic specializations complements of intramembrane particles of cell membranes were unremarkable and did not correlate with presumed high and low resistivity. We propose an equivalent electrical circuit that is consistent with the morphological and physiological observations.