Distribution and morphology of the ampullary organs of the estuarine long-tailed catfish, Euristhmus Upturns (Plotosidae, Siluriformes)

摘要

Ampullary organs of Euristhmus Upturns occur in high densities along the head and in four parallel pathways along the trunk of the body. Large ampullary pores (125-130 mu m) are easily distinguishable from other sensory epithelial pores due to the differences in size and the presence of a collar-like structure. Simple, singular ampullary organs of the head region consist of an ampullary pore connected to along canal with a diameter of 115-175 mu m before terminating as a simple ampulla with an external diameter of 390-480 mu m. The ampullary canal is composed of 1-2layers of flattened squamous epithelial cells, the basement membrane and an interlocking collagen sheath. The innermost cells lining the canal wall are adjoined via tight junctions and numerous desmosomes, as are those of the receptor and supportive cells. Canal wall tissue gives rise to a sensory epithelium containing between 242 and 285 total receptor cells, with an average diameter of 11.7 '± 5.3 intermixed with medially nucleated supportive cells. Each receptor cell (21.38 += 4.41 mu m, height) has apically positioned nucleus and aluminal surface covered with numerous microvilli. Neural terminals abut the basal region of receptor cells opposite multiple presynaptic bodies and densemitochondria. Supportive cells extend from theampullary lumen to the basement membrane, which is adjacent to the complex system of collagen fibres.