Papilla cells may guard the entrance to ampullary organs of Polyodon electroreceptors

Russell, David F.; Ahmetspahic, Melanie; Neiman, Lilia L.

doi:10.1016/j.tice.2022.101868

Cited by 1 publication

(3 citation statements)

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“…A band of numerous elongated papillas (P, Fig 10A–10D ) lined the neck and skin pore of each AO [ 31 ]. Papillas projected into the neck’s lumen, and were angled toward the pore.…”

Section: Resultsmentioning

confidence: 99%

“…The apparent lengths of most WGA + papillas were 6–21 μ. Papillas varied in morphology within an AO’s neck, from short, rounded, and discrete near a pore, to wide, pointed, and partly embedded in the deeper neck. Papillas appeared to join onto (that is, be extensions of) cells making up the cuboidal epithelium lining necks and pores [ 31 ].…”

Section: Resultsmentioning

confidence: 99%

“…The numerous small papillas lining the neck and pore (P, Fig 10 ) may secrete or be coated with defensive molecules, as may the barbs on transitional epithelial cells of ampulla wall (B, Fig 7B–7D ). The functions of papillas and barbs in Polyodon AOs are unknown, but their large numbers and strategic location at the entrance to each AO indicate a defensive role [ 31 ]. The distinct sequential bands of papillas vs. barbs may combat different threats.…”

Section: Discussionmentioning

confidence: 99%

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Lectin binding and gel secretion within Lorenzinian electroreceptors of Polyodon

et al. 2022

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We imaged the carbohydrate-selective spatial binding of 8 lectins in the ampullary organs (AOs) of electroreceptors on the rostrum of freshwater paddlefish (Polyodon spathula), by fluorescence imaging and morphometry of frozen sections. A focus was candidate sites of secretion of the glycoprotein gel filling the lumen of AOs. The rostrum of Polyodon is an electrosensory appendage anterior of the head, covered with >50,000 AOs, each homologous with the ampulla of Lorenzini electroreceptors of marine rays and sharks. A large electrosensory neuroepithelium (EN) lines the basal pole of each AO’s lumen in Polyodon; support cells occupy most (97%) of an EN’s apical area, along with electrosensitive receptor cells. (1) Lectins WGA or SBA labeled the AO gel. High concentrations of the N-acetyl-aminocarbohydrate ligands of these lectins were reported in canal gel of ampullae of Lorenzini, supporting homology of Polyodon AOs. In cross sections of EN, WGA or SBA labeled cytoplasmic vesicles and organelles in support cells, especially apically, apparently secretory. Abundant phalloidin+ microvilli on the apical faces of support cells yielded the brightest label by lectins WGA or SBA. In parallel views of the apical EN surface, WGA labeled only support cells. We concluded that EN support cells massively secrete gel from their apical microvilli (and surface?), containing amino carbohydrate ligands of WGA or SBA, into the AO lumen. (2) Lectins RCA120 or ConA also labeled EN support cells, each differently. RCA120-fluorescein brightly labeled extensive Golgi tubules in the apical halves of EN cells. ConA did not label microvilli, but brightly labeled small vesicles throughout support cells, apparently non-secretory. (3) We demonstrated “sockets” surrounding the basolateral exteriors of EN receptor cells, as candidate glycocalyces. (4) We explored whether additional secretions may arise from non-EN epithelial cells of the interior ampulla wall. (5) Model: Gel is secreted mainly by support cells in the large EN covering each AO’s basal pole. Secreted gel is pushed toward the pore, and out. We modeled gel velocity as increasing ~11x, going distally in AOs (toward the narrowed neck and pore), due to geometrical taper of the ampulla wall. Gel renewal and accelerated expulsion may defend against invasion of the AO lumen by microbes or small parasites. (6) We surveyed lectin labeling of accessory structures, including papilla cells in AO necks, striated ectoderm epidermis, and sheaths on afferent axons or on terminal glia.

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“…A band of numerous elongated papillas (P, Fig 10A–10D ) lined the neck and skin pore of each AO [ 31 ]. Papillas projected into the neck’s lumen, and were angled toward the pore.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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