**17. Liver**

Histopathological analysis reported important alterations in liver, including necrosis, and cytoskeleton disarray, changes in nuclear shape and heterochromatin distribution as well as intense damages in Disse's space between hepatocytes and sinusoid vessels. Increased vacuolization of the endothelial cells, morphological derangement and necrosis in the Disse's space were also evidenced in liver fish exposed to diazinon. These results are in accordance with Cattaneo et al. (2008), who reported disorder in hepatocyte's cords, rupture of the cell membrane and vacuolated cytoplasm in liver tissue of silver catfish, *Rhamdia quelen*, after exposure to 2,4-dichlorophenoxiacetic acid (2,4-D) herbicide. Hypertrophy of hepatocytes, significant increase of kupffer cells, circulatory disturbances, focal necrosis, fatty degeneration, nuclear pycnosis and narrowing of sinusoids has been reported in *G. affinis* and *C. punctatus*, *C. carpio*exposed to deltamethrin and heavy metal, respectively (Cengiz and Unlu, 2006; Mishra and Mohanty, 2008; Vinodhini and Narayanan, 2009). Similar histopathological changes were observed in the liver tissue of *O. niloticus* and *C. carpio* exposed to sub-lethal concentrations of carbaryl and cyfluthrin, respectively (Matos et al., 2007; Sepici-Dinçel et al., 2009). This disturbance in the morphological structure of liver could be associated with a disruption in tissue function, which could be also related to the decreased antioxidant capability in diazinon treated fishes.

**Figure 2.** Histopathology of the liver tissue of rainbow trout (*Oncorhynchus mykiss*) is presented after 28 days of expo‐ sure. (A) Liver of control fish showing hexagonal hepatic cells (HC) surrounded with the sinusoidal portal blood (SI); this histopathological slide shows cord of hepatocytes separated by sinusoids containing erythrocytes; bile duct (GT). (B & E) Liver of 0.1 mg/L of diazinon-treated fish showing increased hypertrophy of hepatocytes (HC), vacuolization of cell cytoplasm (VG), hepatocyte cloudy swelling (CS); and at the same time hepatocytes lost their normal polygonal structure. (C & D & F) Liver of 0.2 mg/L of diazinon-treated fish showing increased cellular degradation with cytoplasm vacuolization (VG) and nucleus atrophy (NA). The hepatic cells form clusters; hypertrophy (HT) and the disorientation in the hepatocytes and bile duct obstruction (GT), hepatocyte cloudy swelling (CS), are found to be more prominent.

Physiological Dysfunction in Fish After Insecticides Exposure

http://dx.doi.org/10.5772/54742

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The head kidney of teleost fish is composed of a variety of cells, including parenchymal cells, lymphoid and hematopoietic tissues (Mela et al., 2007). The functional unit of the kidney is nephron. Morphologically, the nephron of bony fish includes glomerulus, tubules and collecting ducts. In the fish exposed to 0.1 mg/L diazinon, disorientation in the glomerular structure, dilation in the inter space of urinary tubular, cloudy swelling were observed. Histopathological damage in the kidney tissues of fish exposed to 0.2 mg/L diazinon were characterized by degeneration in the epithelial cells of renal tubule, necrosis in the hematopoietic tissue, degeneration of glomerulus, dilation of glomerular capillaries, appearance of vacuoles in cytoplasm epithelial cells of renal tubules with hypertrophied cells and narrowing of the tubular lumen. Increase of ROS production in the diazinon metabolism

Figures are representatives of three replicate experiments (magnification of the sections 400X).

**18. Kidney**

**Figure 1.** Gills of rainbow trout from the control group (A): Lamella (L), erythrocyte in lamellar capillary (ELC), Chloride cell (CC), Pillar cell (PC), Chondrocytes (CO); Gills of rainbow trout exposed to 0.01 mg/L diazinon (B): crusting and necrosis of secondary lamellae's epithelium (C&N), mucosa cell hyperplasia (MH), clubbing tips of gill filaments (CT); Gills of rainbow trout exposed to 0.02 mg/L diazinon (C): Changes in cartilage tissue of the gill filament, fusion of sec‐ ondary lamellae (FSL), edema and epithelial hyperplasia (Ed), and the loss of the secondary filaments. Figures are rep‐ resentatives of three replicate experiments (magnification of the sections 400X).

**Figure 2.** Histopathology of the liver tissue of rainbow trout (*Oncorhynchus mykiss*) is presented after 28 days of expo‐ sure. (A) Liver of control fish showing hexagonal hepatic cells (HC) surrounded with the sinusoidal portal blood (SI); this histopathological slide shows cord of hepatocytes separated by sinusoids containing erythrocytes; bile duct (GT). (B & E) Liver of 0.1 mg/L of diazinon-treated fish showing increased hypertrophy of hepatocytes (HC), vacuolization of cell cytoplasm (VG), hepatocyte cloudy swelling (CS); and at the same time hepatocytes lost their normal polygonal structure. (C & D & F) Liver of 0.2 mg/L of diazinon-treated fish showing increased cellular degradation with cytoplasm vacuolization (VG) and nucleus atrophy (NA). The hepatic cells form clusters; hypertrophy (HT) and the disorientation in the hepatocytes and bile duct obstruction (GT), hepatocyte cloudy swelling (CS), are found to be more prominent. Figures are representatives of three replicate experiments (magnification of the sections 400X).
