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Quantitative histopathology of Oreochromis niloticus gills after copper exposure
Author(s) -
Monteiro S. M.,
Rocha E.,
FontaínhasFernandes A.,
Sousa M.
Publication year - 2008
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.2008.02009.x
Subject(s) - gill , oreochromis , histopathology , biology , copper , necrosis , epithelium , anatomy , nile tilapia , pathology , fishery , fish <actinopterygii> , materials science , medicine , metallurgy , genetics
In order to test whether histopathological changes of gills demonstrated a good dose–response relationship with water copper levels, juvenile Nile tilapia Oreochromis niloticus , of both sexes and similar mass (36·3 + 7·7 g), were kept in dechlorinated tap water (temperature 25° C, range ±1° C; pH 6·5–7·5; hardness 74·5 mg l −1 CaCO 3 ) and exposed to 40 and 400 μg l −1 of copper. Gill samples were collected after 3, 7, 14 and 21 days. Six major histopathological changes (oedema, lifting, changes in filament epithelium thickness, lamellar fusion, vasodilatation and aneurisms) and three minor ones (proliferation of the lamellar epithelium, necrosis and adjacent lamellar fusion) were found and their prevalence estimated. The extent and severity of each histopathological change were used to develop a severity gradation scale (SGS). Semi‐quantitative analysis of the histopathological changes and measurements of gill copper deposition levels revealed a good dose– and time–response relationship. Oedemas and aneurisms were significantly correlated with acute exposure periods and lamellar fusion with chronic exposure. Epithelial lifting and changes in filament epithelial thickness were seen at lower and higher metal concentrations, respectively. The data also revealed that the SGS profile of each lesion was dependent of gill copper burden.