摘要:

Abstract.The structural changes which occur in the heart, the lateral muscle and the large intestine during the development of cold water vibriosis in Atlantic salmon,Salmo salarL., have been studied by light and electron microscopy. The results strongly suggest a causative relationship between the presence of the fish pathogen,Vibrio salmonicida, and the observed pathological changes. Cell damage was invariably accompanied by the presence of the bacterium. A close relationship was found between the number of bacteria detected in the tissues and the degree of morphological damage. The most severe cell damage was found in areas with a rich blood supply. The earliest sign of damage was detected in the cell coat and cell membrane on the luminal side of the endothelial cells of the capillaries. Later in the development, the bacteria were also found intracellularly in endothelial cells. In moribund fish, the cells in the vicinity of the capillaries were also severely damaged. Bacteria appeared intracellularly in leucocytes even in early stages of the disease. This caused more severe damage to leucocytes compared to erythrocytes, which seldom contained bacteria.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00518.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.A hitherto unrecorded haplosporean was found in the hepatopancreas ofPenaeus vannamei. Multinucleate plasmodia developing within the hepatocytes fragment into unimicleate stages. Eventually the host cells are destroyed and the uninuclear stages are released into the lumen of the secretory tubules. The haplosporosomes are oval, have a thick cortex and contain a small spherical medulla at the broader end. No spores were found and thus the parasite, which is highly pathogenic, could not be assigned any precise taxonomic position.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00519.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Juvenile rainbow trout were exposed to 36, 171, 1017 and 4887 mg/1 of suspended kaolin clay for 64 days. Gills were analysed qualitatively and quantitatively using histology. Branchial pathology was absent at all sample times in fish exposed to 36, 171 and 1017 mg/1 kaolin, although intracellular kaolin was visible within filament and lamellar epithelium in gills exposed to 171, 1017 and 4887 mg/1 kaolin at 4, 8, 16, 32 and 64 days. Lesions were found in gills exposed to 4887 mg/1 kaolin at 16 and 32 days but the marked lamellar proliferation was associated with moderate to large numbers of protozoa identified asIchthyobodo necator. Gills regained normal architecture by 64 days despite continued exposure to kaolin. It is suggested that while the gill lesions were probably a direct result of protozoan infection, kaolin was indirectly responsible for creating a favourable environment for protozoan colonization. The recovery of normal architecture and reduction of protozoan numbers between 32 and 64 days was probably a function of increased mucus secretion, immune response and turnover of branchial epithelium. The authors conclude that exposure to prevailing levels of this inert clay particle, even for periods as long as 64 days, probably has little direct effect on gill structure at the light microscope level. The action of non‐inert and organic particles remains to be investigate

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00520.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Gyrodactylus salariswas probably introduced into the River Vefsna, a large salmon river in northern Norway, by stocking of Atlantic salmon smolts from infected hatcheries in 1975 and 1977. An outbreak ofG. salarisamong salmon parr was observed in 1978. During the following 2 years, the parasite spread throughout the entire watercourse. There was a rapid rise in prevalence rate and degree of infection. The density of salmon parr decreased from a high level before theGyrodacrylusoutbreak to close to zero after the outbreak. Salmon parr mortality is probably associated with an increase in the parasite burden. Infected fish appear to survive for slightly more than 1 year and this time period is sufficient for transmission of the parasite to the next year class. The total catch of salmon ascending the river has also greatly decreased in recent years.

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00521.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.An epidemic of cutaneous tumours occurs in northern pike,Esox luciusL., from the Åland Islands of Finland. Previous studies have shown that the neoplasm is of mesenchymal origin and that it is not of B‐lymphocytic lineage; however, a T‐lympho‐cytic origin could not be totally excluded. Here the authors provide morphologic evidence that the tumour could, in fact, be monocyte derived. The close apposition of the tumour cells with a lack of cell‐cell junctions is in keeping with the view that it is not of epithelial origin. A striking morphologic characteristic of the tumour cells is the presence of groups of lysosomes and large numbers of cytoplasmic lipid droplets. Therefore, the authors suggest that the tumour cells have features of histiomonocytic cells and that the neoplasm might be a piscine analogue of true histiocytic lymphoma in humans. These studies represent the first description of this type of neoplasm

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00522.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Parasitic cells resembling amoeba trophozoites were found histologically and ultrastructurally to be associated with severe proliferate gill disease and systemic infection often leading to extensive granulomatous tissue changes in the European catfish,Silurus glanisL. Infections with the normally free‐living amoeba leading to mortalities of up to 30% were considered to result from suboptimal water quality with heavy bacterial loading in a heated partial recirculation syste

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00523.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract.Sublethal exposure of rainbow trout fry,Salmo gairdneriRichardson, to polychlorinated biphenyls (PCBs) or 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) did not significantly affect mortality or mean time to death following challenge with infectious haematopoietic necrosis virus (IHNV). Rainbow trout fry were fed experimental diets containing 0, 5. 50 or 500 μg/g of the technical polychlorinated biphenyl mixture, Aroclor 1254, for 30 days or were injected intraperitoneally with graded single doses of TCDD. Fish from each treatment group were challenged by immersion exposure to IHNV. At early time points following virus challenge, histopathologic lesions due to virus disease were more severe and occurred more frequently in virus‐challenged fish which received either toxicant than in virus‐challenged control fish. Taken together, these findings suggest that rainbow trout are less sensitive than mammalian species to the sublethal effects of these structurally related toxicants on resistance to viral disease. However, a subtle effect of these chemicals on the pathogenesis of the virus disease is suggested by the histopatho

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00524.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00525.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00526.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0140-7775    

DOI:10.1111/j.1365-2761.1988.tb00527.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY