title: Unitubulotestis sardae (Trematoda: Didymozoidae) infection in Atlantic bonito Sarda sarda (Perciformes: Scomberomoridae) in the Ionian and Tyrrhenian Seas: histopathological and SEM investigations.
abstract: Nematobothrinae are trematoda digenea that usually live in cysts in fish tissues. They have been reported in different teleost species although the host-parasite relationships remain to be elucidated. This report is aimed at analysing the presence of Unitubulotestis sardae in the Atlantic bonito (Sarda sarda) populations fished in the Straits of Messina. The histopathological change reported in literature in similar cases is an aneurisma verminosa saccata, whereas, in the specimens here described, we show neovascularisation and at the same time, hyperplasia of the gill epithelium, leading to the formation of a bistratified cystic wall. The SEM examination of the parasitic cysts gave us a better understanding of the surface microanatomical details of the cystic walls. The external surface appeared to be constituted by a pluristratified covering epithelium of the gill arch. The internal layer was constituted by a net of blood vessels richly anastomosed with those originating from the gill arch arteries. This could be in agreement with data reported by Grabda (1947) on the localisation of the juvenile stages of the parasite in this blood vessel, but the evolution in cysts formation does not show similarities with the formation of an aneurisma.
authors.affiliation: Department of Veterinary Public Health, Faculty of Veterinary Medicine, University of Messina, University Centre of Annunziata, Messina, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Marino
authors.forename: S
authors.initials: S
authors.lastname: Giannetto
authors.forename: M
authors.initials: M
authors.lastname: Cavallaro
authors.forename: M L
authors.initials: ML
authors.lastname: Paradiso
authors.forename: T
authors.initials: T
authors.lastname: Bottari
authors.forename: G
authors.initials: G
authors.lastname: De Vico
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000469:parasitology / Q000648:ultrastructure; D005260:Female; D005393:Fish Diseases / Q000469:parasitology* / Q000473:pathology; D005399:Fishes / Q000469:parasitology*; D005880:Gills / Q000098:blood supply / Q000469:parasitology / Q000648:ultrastructure; D006790:Host-Parasite Interactions; D007558:Italy; D008297:Male; D008522:Mediterranean Sea; D008854:Microscopy, Electron / Q000662:veterinary; D009389:Neovascularization, Pathologic; D010273:Parasitic Diseases, Animal / Q000473:pathology*; D014200:Trematoda / Q000302:isolation & purification / Q000502:physiology* / Q000648:ultrastructure; D014201:Trematode Infections / Q000662:veterinary*