Article

Zeitschrift für Zellforschung und Mikroskopische Anatomie

, Volume 130, Issue 3, pp 362-377

The lorenzinian ampullae of Polyodon spathula

  • J. Mørup JørgensenAffiliated withInstitute of Comparative Anatomy
  • , Å. FlockAffiliated withKing Gustaf Vth Research InstituteDept. of Otolaryngology, Karolinska Sjukhuset
  • , J. WersällAffiliated withKing Gustaf Vth Research InstituteDept. of Otolaryngology, Karolinska Sjukhuset

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Summary

Light and electron microscopic observations on the ampullary organs of Polyodon spathula (Chondrostei, Osteichthyes) reveal a sensory epithelium similar to that found in the Lorenzinian ampulla, an electroreceptor found in marine Elasmobranchs.

The sensory cells have a very small luminal part provided with a cilium. They are innervated by many nerve endings. Each nerve fibre apparently makes synaptic contact with several sensory cells. The synaptic structure in the sensory cell is composed of a flat sheet, the outermost part of which is surrounded by 3 or 4 annuli of densely staining material. The sheet extends into a protrusion of the sensory cell, and there is a corresponding invagination in the nerve terminal.

The conclusion that these organs are electroreceptors, is supported by the finding that the fish responds to the introduction of an iron tube in the aquarium, whereas a wooden rod introduced in the same way causes no response.

Key-words

Lorenzinian ampullae Polyodon spathula Sensory epithelium Synapses Electron microscopy