On the ampullary organs of the South-American paddle-fish Sorubim lima (Siluroidea, Pimelodidae)

Abstract

Ampullary organs were found in the epidermis of the paddle-fish Sorubim lima; they are distributed all over the skin surface of the fish but are particularly densely grouped in the head region and on the dorsal surface of the paddle. Histological and electron microscopical observations show that their structure is similar to the type of cutaneous ampullary organs characteristic of other Siluroidea. Composed of a relatively large mucus-filled ampulla, the organ possesses a short and narrow canal which leads to the outer epidermal surface. The wall of the ampulla is formed of several layers of flat epidermal cells. In general four sensory cells, each one surrounded by supporting cells, compose the sensory epithelium at the bottom of the ampulla. The inner surface of the sensory cells in contact with the ampullary mucus bears only microvilli. The contact between the nerve endings and the sensory cells show the characteristic structure of an afferent neuro-sensory junction. Two ampullae are innervated in some cases by the same afferent nerve fibre.

The Electrosensory Cells of the Ampullary Organ of the Transparent Catfish (Kryptopterus bicirrhus)

“…The distribution of the ampullary organs of the transparent catfish as well as their morphology has previously been described by Wachtel and Szamier (1969). The sensory epithelium is similar to that described from ampullary organs of other catfish, for example, Amiurus (Icfalurus) nebulosus (Mullinger 1964), Sorubim lima (Gelinek 1978), Silurus glank (Jakubowski 1987) and Silurus asofus (Sato & Katagiri 1988). The sensory cells have apical microvilli and no cilium, as in normal teleost electrosensory cells, in contrast to the ciliated electroreceptors in Lorenzinian ampullae found in elasmobranchs and nonteleost bony fish (Zakon 1986).…”

Microampullary organs of a freshwater eel‐tailed catfish, plotosus (tandanus) tandanus

“…The large, circular, centrally located nucleus observed in P. tandanus is characteristic of ampullary receptor cells (Zakon, 1986). The low number of receptor cells (10 -15) in P. tandanus resembles that of other freshwater siluroids (Herrick, 1901;Sato, 1956;Szabo, 1974;Gelinek, 1978;Srivastava and Seal, 1981;Zakon, 1986;Jakubowski, 1987), but is different from the hundreds of receptor cells per ampulla in P. anguillaris (Obara, 1976;Zakon, 1986).…”

“…They show closer affinity to those of freshwater Siluriformes (Herrick, 1901;Sato, 1956;Szabo, 1974;Gelinek, 1978;Srivastava and Seal, 1981;Zakon, 1986;Jakubowski, 1987) and have variations that resemble the differences between the freshwater ray Potamotrygon circularis and marine elasmobranchs (Szabo et al, 1972;Zakon, 1986).…”

Problems in catfish anatomyand phylogeny as exemplified by theNeotropical Hypopthalmidae (Teleostei: Siluroidei)

“…Of the taxa examined Iheringichthys has a similar jelly-like material in the lower lip, but it is concentrated in ampullae in the tissue close to the jaw symphysis and not arranged in widely spaced rows. Gelinek (1978) has described ampullary organs in the epidermis of Sorubim. He found them to be densely grouped in the labial tissue of the upper jaw and noted their structural similarity to those organs in Plotosus.…”