title: Selected pathological, immunohistochemical and ultrastructural changes associated with an infection by Diphyllobothrium dendriticum (Nitzsch, 1824) (Cestoda) plerocercoids in Coregonus lavaretus (L.) (Coregonidae).
abstract: The pathological changes induced by an infection of Diphyllobothrium dendriticum (Nitzsch, 1824) plerocercoids in powan, Coregonus lavaretus (L.), from Loch Lomond, Scotland, were assessed using immunohistochemical and ultrastructural techniques. In a sample of 26 powan, the occurrence of encysted plerocercoids of D. dendriticum on the outer surface of the stomach was 38.5% (n = 10) with the number of cysts ranging from 4 to 15 and measuring 4.2 +/- 1.0 mm x 3.4 +/- 0.9 mm (mean +/- SD). Histological examination of intestinal samples also revealed plerocercoids (2-21) encapsulated within a proliferation of mesenteric fibrous tissues of the gastric wall and, occasionally, by the gut lamina propria-submucosa and lamina muscularis. In section, cysts were tri-layered and were formed from a series of concentric whorls of fibroblast and collagen fibre-based connective elements. The extent of necrosis within each muscle layer and the serosa of the stomach differed, notably within the latter that was marked by a chronic inflammatory reaction and fibrosis. Within the cyst and around it, a large number of degranulating mast cell/eosinophilic granule cells were seen, in addition to melano-macrophage centres. Immunohistochemical staining of sections of infected stomach revealed a high density of elements, in close proximity to plerocercoids, staining positive for serotonin, bombesin, substance P and galanin. Uninfected material did not present the same levels of activity. Sections through both infected and uninfected tissue were also tested for elements containing vasoactive intestinal peptide, met-enkephalin, calcitonin gene-related peptide, neuropeptide Y and nitric oxide synthase, but these were absent.
authors.affiliation: Department of Biology, University of Ferrara, Ferrara, Italy. dzb@unife.it
authors.forename: B S
authors.initials: BS
authors.lastname: Dezfuli
authors.forename: F
authors.initials: F
authors.lastname: Pironi
authors.forename: E
authors.initials: E
authors.lastname: Simoni
authors.forename: A P
authors.initials: AP
authors.lastname: Shinn
authors.forename: L
authors.initials: L
authors.lastname: Giari
mesh_terms: D000818:Animals; D001839:Bombesin / Q000032:analysis; D004169:Diphyllobothriasis / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D004170:Diphyllobothrium / Q000472:pathogenicity*; D005393:Fish Diseases / Q000276:immunology* / Q000469:parasitology / Q000473:pathology*; D019004:Galanin / Q000032:analysis; D007106:Immune Sera / Q000276:immunology / Q000378:metabolism; D007150:Immunohistochemistry / Q000662:veterinary; D011817:Rabbits; D051381:Rats; D012487:Salmonidae / Q000469:parasitology*; D012701:Serotonin / Q000032:analysis; D013270:Stomach / Q000469:parasitology / Q000473:pathology / Q000648:ultrastructure; D013373:Substance P / Q000032:analysis; D013552:Swine
chemical_list: D007106:Immune Sera; D012701:Serotonin; D013373:Substance P; D019004:Galanin; D001839:Bombesin