Sublethal toxicity of organophosphate, diazinon on some organs of great sturgeon ( Huso huso )

Sublethal toxicity effects of diazinon on the struc - ture of some organs of great sturgeon ( Huso huso ) were investigated. Diazinon was applied at a sub- lethal concentration of 1.5 mg L -1 at 22±1 ?C for nine weeks as a constant bath. Tissues of liver, kidney and gills were sampled and examined histo- pathologically after 1, 14, 28, 42 and 63 days post exposure to the toxicant. The results of light micro - scopic examinations of tissues revealed congestion of blood vessels, pyknosis and cloudy swelling in hepatocytes. Congestion of blood vessels and thick - ening of the basal membrane of bowman capsule in glumerol of the kidney were also observed. The gill of fi sh exposed to toxicant also showed congestion and dilation of blood vessels, swelling of the base - ment membrane, hyperplasia, fusion and necrosis of lamellae. This data showed that a long term expo - sure of fi sh to diazinon can cause several patholog - ical changes in respiratory organ, haematopoietic tissues and liver.