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The impact of Anguillicoloides crassus (Nematoda) on European eel swimbladder: histopathology and relationship between neuroendocrine and immune cells

Published online by Cambridge University Press:  13 January 2021

Bahram Sayyaf Dezfuli Open the ORCID record for Bahram Sayyaf Dezfuli [Opens in a new window] ,
Chiara Maestri ,
Massimo Lorenzoni ,
Antonella Carosi ,
Barbara J Maynard  and
Giampaolo Bosi
Bahram Sayyaf Dezfuli*
Affiliation:
Department of Life Sciences and Biotechnology, University of Ferrara, St. Borsari 46, 44121Ferrara, Italy
Chiara Maestri
Affiliation:
Department of Life Sciences and Biotechnology, University of Ferrara, St. Borsari 46, 44121Ferrara, Italy
Massimo Lorenzoni
Affiliation:
Department of Cellular and Environmental Biology, University of Perugia, St. Elce di sotto 5, 06123Perugia, Italy
Antonella Carosi
Affiliation:
Department of Cellular and Environmental Biology, University of Perugia, St. Elce di sotto 5, 06123Perugia, Italy
Barbara J Maynard
Affiliation:
The Institute for Learning and Teaching, Colorado State University, Fort Collins, CO80523, USA
Giampaolo Bosi
Affiliation:
Department of Health, Animal Science and Food Safety, Università degli Studi di Milano, St. Trentacoste 2, 20134Milan, Italy
*
Author for correspondence: Bahram Sayyaf Dezfuli, E-mail: dzb@unife.it
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Abstract

The swimbladder functions as a hydrostatic organ in most bony fishes, including the European eel, Anguilla anguilla. Infection by the nematode Anguillicoloides crassus impairs swimbladder function, significantly compromising the success of the eel spawning migration. Swimbladders from 32 yellow eels taken from Lake Trasimeno (Central Italy) were analysed by histopathology- and electron microscopy-based techniques. Sixteen eels (50%) harboured A. crassus in their swimbladders and intensity of infection ranged from 2 to 17 adult nematodes per organ (6.9 ± 1.6, mean ± s.e.). Gross observations of heavily infected swimbladders showed opacity and histological analysis found a papillose aspect to the mucosa and hyperplasia of the lamina propria, muscularis mucosae and submucosa. Inflammation, haemorrhages, dilation of blood vessels and epithelial erosion were common in infected swimbladders. In the epithelium of parasitized swimbladders, many empty spaces and lack of apical junctional complexes were frequent among the gas gland cells. In heavily infected swimbladders, we observed hyperplasia, cellular swelling and abundant vacuolization in the apical portion of the gas gland cells. Numerous mast cells and several macrophage aggregates were noticed in the mucosal layer of infected swimbladders. We found more nervous and endocrine elements immunoreactive to a panel of six rabbit polyclonal antibodies in infected swimbladders compared to uninfected.

Keywords

Cellular responseseelnematodeneuronal changesswimbladder
Type
Research Article
Information
Parasitology , Volume 148 , Issue 5 , April 2021 , pp. 612 - 622
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Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press

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