**18. Kidney**

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

122 Insecticides - Development of Safer and More Effective Technologies

**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).

treated fishes.

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 process may play an important role in lipid peroxidation of components of cellular membrane resulting in reduced nephron number, glomerular lesions, and reduced glomerular filtration rate. Similar studies showed the toxic effect of insecticides on the histology of kidney of Atlantic salmon (*Salmo salar*), rainbow trout, *O. mykiss*, exposed to endosulfan, as pesticide and captan, as the fungicide, respectively (Glover et al., 2007; Boran et al., 2012). These results conform to the deltamethrin and heavy metals effects on kidney tissue of carp that have been reported by Cengiz, (2006) and Vinodhini and Narayanan (2009).

### **19. Spleen**

The spleen has a fibrous capsule, and small trabeculae extend into the parenchyma, which can be divided into a red and white pulp. In rainbow trout, the aggregations of melanomacrophages are less well-defined and lack a capsule, but the association with blood vessels and lymphocytes is maintained (Press and Evensen, 1999). Expansion of red pulp with vascular congestion and a significant deposition of hemosiderin granules in a melano-macrophage center are important histopathological damages observed in spleen of fish exposed to both concentrations of diazinon. One of the typical macroscopic changes associated with diazinon toxicity is enlargement and roughness of the spleen. These results are similar to the 3,4 dichloroaniline and captanin effects that have been described in common goby (*Pomatoschis tusmicrops*) and rainbow trout, respectively (Monteiro et al., 2006; Boran et al., 2012).

### **20. Digestive tract (intestine)**

The intestine of rainbow trout has a mucosa, submucosa, muscularis and serous membrane. The mucosa epithelium has thin and elongated absorptive cells or enterocytes, goblet cells and lymphocytes. Enterocytes are a single layer of columnar cells with apical brush border and basal elongated nucleus with one nucleolus. There are also often lymphocytes at the basal and apical regions of the epithelium. Atrophy and necrosis of mucosal cell, exfoliate of mucosal epithelium, lymphocyte infiltration to lamina propia, reduction in the elastic properties and capillary bleeding in intestine tissue are important histopathological alterations observed in fish exposed to both concentrations of diazinon. Necrosis, degeneration, and accumulation of lymphocyte in lamina propia were observed in the intestine of mosquitofish, *G. affinis*, exposed to Thiodan and deltamethrin (Cengiz et al., 2001;Cengiz and Unlu, 2006) and *Cirrhinus mrigala* treated with lambda-cyhalothrin (Velmurugan et al., 2007). This result is similar to the observations by Glover et al. (2007) in Atlantic salmon (*S. salar*) to dietary endosulfan exposure.

#### **21. Gonads**

Some insecticides induced histopathological changes in testes are difficult to study by light mi‐ croscopy because of the small sizes of the affected cells. Decrease in number and condensation of spermatogonic cells and appearance of a large number of intertubular vacuoles, cloudy swelling and necrosis of seminiferous tubules are important histopathological alterations ob‐ served in testis of fish exposed to diazinon (Duttaa & Meijer, 2003; Banaee et al., 2009). This is particularly evident with Sertoli cells, which may undergo major insecticides induced changes in morphology. Thus, Spermatocyte necrosis appears to be a common result of diazinon expo‐

**Figure 3.** Kidney of rainbow trout from the control group (A): Hematopoietic tissue (HT), renal tube (RT), Glomerulus (GL), Bowman capsule (BC); kidney of rainbow trout exposed to 0.01 mg/L diazinon (B): dilation in inter space of uri‐ nary tubular (DUT), cloudy swelling (CS), glomerular destruction; kidney of rainbow trout exposed to 0.02 mg/L diazi‐ non (C): degeneration of tubular epithelial cells (EC), proliferation of epithelial cells in Bowman capsule, cloudy swelling (CS), severe necrosis in nephritic tissue (Nc). Figures are representatives of three replicate experiments (mag‐

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sure (Banaee et al., 2009).

nification of the sections 400X).

process may play an important role in lipid peroxidation of components of cellular membrane resulting in reduced nephron number, glomerular lesions, and reduced glomerular filtration rate. Similar studies showed the toxic effect of insecticides on the histology of kidney of Atlantic salmon (*Salmo salar*), rainbow trout, *O. mykiss*, exposed to endosulfan, as pesticide and captan, as the fungicide, respectively (Glover et al., 2007; Boran et al., 2012). These results conform to the deltamethrin and heavy metals effects on kidney tissue of carp that have been reported by

The spleen has a fibrous capsule, and small trabeculae extend into the parenchyma, which can be divided into a red and white pulp. In rainbow trout, the aggregations of melanomacrophages are less well-defined and lack a capsule, but the association with blood vessels and lymphocytes is maintained (Press and Evensen, 1999). Expansion of red pulp with vascular congestion and a significant deposition of hemosiderin granules in a melano-macrophage center are important histopathological damages observed in spleen of fish exposed to both concentrations of diazinon. One of the typical macroscopic changes associated with diazinon toxicity is enlargement and roughness of the spleen. These results are similar to the 3,4 dichloroaniline and captanin effects that have been described in common goby (*Pomatoschis*

*tusmicrops*) and rainbow trout, respectively (Monteiro et al., 2006; Boran et al., 2012).

The intestine of rainbow trout has a mucosa, submucosa, muscularis and serous membrane. The mucosa epithelium has thin and elongated absorptive cells or enterocytes, goblet cells and lymphocytes. Enterocytes are a single layer of columnar cells with apical brush border and basal elongated nucleus with one nucleolus. There are also often lymphocytes at the basal and apical regions of the epithelium. Atrophy and necrosis of mucosal cell, exfoliate of mucosal epithelium, lymphocyte infiltration to lamina propia, reduction in the elastic properties and capillary bleeding in intestine tissue are important histopathological alterations observed in fish exposed to both concentrations of diazinon. Necrosis, degeneration, and accumulation of lymphocyte in lamina propia were observed in the intestine of mosquitofish, *G. affinis*, exposed to Thiodan and deltamethrin (Cengiz et al., 2001;Cengiz and Unlu, 2006) and *Cirrhinus mrigala* treated with lambda-cyhalothrin (Velmurugan et al., 2007). This result is similar to the observations by Glover et al. (2007) in Atlantic salmon (*S. salar*) to dietary endosulfan exposure.

Some insecticides induced histopathological changes in testes are difficult to study by light mi‐ croscopy because of the small sizes of the affected cells. Decrease in number and condensation

Cengiz, (2006) and Vinodhini and Narayanan (2009).

124 Insecticides - Development of Safer and More Effective Technologies

**20. Digestive tract (intestine)**

**19. Spleen**

**21. Gonads**

**Figure 3.** Kidney of rainbow trout from the control group (A): Hematopoietic tissue (HT), renal tube (RT), Glomerulus (GL), Bowman capsule (BC); kidney of rainbow trout exposed to 0.01 mg/L diazinon (B): dilation in inter space of uri‐ nary tubular (DUT), cloudy swelling (CS), glomerular destruction; kidney of rainbow trout exposed to 0.02 mg/L diazi‐ non (C): degeneration of tubular epithelial cells (EC), proliferation of epithelial cells in Bowman capsule, cloudy swelling (CS), severe necrosis in nephritic tissue (Nc). Figures are representatives of three replicate experiments (mag‐ nification of the sections 400X).

of spermatogonic cells and appearance of a large number of intertubular vacuoles, cloudy swelling and necrosis of seminiferous tubules are important histopathological alterations ob‐ served in testis of fish exposed to diazinon (Duttaa & Meijer, 2003; Banaee et al., 2009). This is particularly evident with Sertoli cells, which may undergo major insecticides induced changes in morphology. Thus, Spermatocyte necrosis appears to be a common result of diazinon expo‐ sure (Banaee et al., 2009).

**Figure 4.** Spleen of rainbow trout from the control group (A): With pulp (WP), Red Pulp (RP), Spleen of rainbow trout exposed to 0.01 mg/L diazinon (B): Melanomacrophage centers (MC), Ellipsoid cells (EC), Penicillus (P), Expansion of splenic red pulp and melano-macrophage centers, disorientation in ellipsoid cells; Spleen of rainbow trout exposed to 0.02 mg/L diazinon (C): Disorder in ellipsoid cells, the increase of number and size of melano-macrophage centers, and cloudy swelling in spleen tissue (CS). Figures are representatives of three replicate experiments (magnification of the sections 400X).

The ovaries of *C. carpio* have shown significant changes on exposure to sub-lethal concentra‐ tion of diazinon. The oocyte with de-shaped yolk vesicles, vacuolated follicular epithelium and degenerative cytoplasm were reported in fish exposed to diazinon by Banaee et al., 2008.

> munological parameters. In addition, the histopathological analysis performed in gills, liver, spleen, kidney, gonads and intestine of fish exposed to different concentration of insecticides reported significant damage in all tissues indicating that it was a useful methodology for moni‐ toring the effects of insecticides on wild and cultured fish. These changes may be potentially disruptive for the survivability of fish in aquaculture farm and natural resources. This fact should be taken into consideration when this insecticide is used for pest control in agriculture

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

**Figure 5.** Intestine of rainbow trout from the control group (A): Mucosal epithelium (ME), Lamia's propria (LP), Submucosa layer (SML), Muscularis layer (ML), Serosa layer (SL). Intestine of rainbow trout exposed to 0.01 mg/L diazinon (B): Desquamating of the mucosal epithelium; Intestine of rainbow trout exposed to 0.02 mg/L diazinon (C): Mucosal epithelial hyperplasia, severe necrosis in the mucous layer, loss of the intestine microvilli, disorganization in arrange‐ ment of circular and longitudinal muscles in muscularis layer, loss of muscle elasticity and flexibility of the intestine.

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fields surrounding surface water and ground water resources.
