Histological effects of the inert suspended clay ...
|Title||Histological effects of the inert suspended clay kaolin on the gills of juvenile rainbow trout, Salmo gairdneri Richardson|
|Author(s)||S. A. Goldes, H. W. Ferguson, R. D. Moccia, Pierre Y. Daoust|
|Journal||Journal of Fish Diseases|
|Abstract||Juvenile rainbow trout were exposed to 36, 171, 1017 or 4887 mg/litre of suspended kaolin clay for 64 days. Gills were analysed qualitatively and quantitatively using histology. Branchial pathology was absent at all sample times exposed to 36, 171 and 1017 mg/litre kaolin, although intracellular kaolin was visible within filament and lamellar epithelium in gills exposed to 171, 1017 and 4887 mg/l kaolin at 4, 8, 16, 32 and 64 days. Lesions were found in gills exposed to 4887 mg/l kaolin at 16 and 32 days but the pronounced lamellar proliferation was associated with moderate to large numbers of protozoa identified as Ichthyobodo 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. It is concluded that exposure to prevailing levels of this inert clay particle, even for periods as long as 64 days, probably has litle direct effect on gill structure at the light microscopic level..|
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