Ultrastructure of the ampullae of Lorenzini of <Emphasis Type="Italic">Aptychotrema rostrata</Emphasis> (Rhinobatidae) |
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Authors: | Barbara E Wueringer Ian R Tibbetts Darryl L Whitehead |
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Institution: | (1) Department of Zoology, University of Vienna, 1090 Vienna, Austria;(2) Centre for Marine Studies, The University of Queensland, St Lucia, QLD, 4072, Australia;(3) Present address: Sensory Neurobiology Group (formerly Vision, Touch and Hearing Research Centre), School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, 4072, Australia |
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Abstract: | Small epidermal pores of the electrosensory ampullae of Lorenzini located both ventrally and dorsally on the disk of Aptychotrema rostrata (Shaw and Nodder, 1794) open to jelly-filled canals, the distal end of which widens forming an ampulla that contains 6 ± 0.7
alveolar bulbs (n = 13). The sensory epithelium is restricted to the alveolar bulbs and consists of receptor cells and supportive cells. The
receptor cells are ellipsoid and their apical surfaces are exposed to the alveolar lumen with each bearing a single central
kinocilium. Presynaptic bodies occur in the basal region of the receptor cell immediately proximal to the synaptic terminals.
The supportive cells that surround receptor cells vary in shape. Microvilli originate from their apical surface and extend
into the alveolar lumen. Tight junctions and desmosomes connect the supportive cells with adjacent supportive and receptor
cells in the apical region. The canal wall consists of two cell layers, of which the luminal cells are squamous and interconnect
via desmosomes and tight junctions, whereas the cells of the deeper layer are heavily interdigitated, presumably mechanically
strengthening the canal wall. Columnar epithelial cells form folds that separate adjacent alveoli. The same cells separate
the ampulla and canal wall. An afferent sensory nerve composed of up to nine myelinated nerve axons is surrounded by several
layers of collagen fibers and extends from the ampulla. Each single afferent neuron can make contacts with multiple receptor
cells. The ultrastructural characteristics of the ampullae of Lorenzini in Aptychotrema rostrata are very similar to those of other elasmobranch species that use electroreception for foraging. |
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Keywords: | Ampullae of Lorenzini Alveolar bulbs Receptor cell Aptychotrema rostrata Electroreception |
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