**3.5 Electron microscope examination of hepatocytes**

The fine structure of the hepatocytes shows parallel cisternae of rough endoplasmic reticulum (rer), polygonal centrally located vesicular nuclei (n) with nucleolus (nu), numerous mitochondria (m) with different shapes and sizes and Golgi complex (g) near the nucleus (Fig. 6a).

Hepatocytes of animals exposed to 0.05 mg/l of 4-nonylphenol appeared swollen or hypertrophied with dense bodies (db), karyolysis in nucleus (fig. 6b) and damaged mitochondria (dm), rarified cytoplasm (rc) and vacuoles (v) (fig. 7b). Also, degenerative changes, shrunken and indented nuclei with cytoplasmic fat droplets (fd) were observed (Fig. 8b). In fishes exposed to 0.08 mg/l of 4-nonylphenol the cytoplasm shows tiney vacuoles (cv), the nuclei appeared irregular in shape with nuclear indentation. Some hepatocytes showed signs of karylyosis (Fig. 7a, 9a). Moreover, damaged mitochondria, degenerative rough endoplasmic reticulum (drer), increase in number of lysosomes (ly) were recorded. Some nuclei showed condensation and migration of chromatin at the nuclear periphery with prominent nucleolus with some apoptotic changes in the form of nuclear envelope (Fig. 9a). Some hepatocytes appeared swollen with large rarified areas in the cytoplasm resulting in disorganization and dissociation of cellular organelles (Fig. 7a). Hepatocytes of fishes exposed to 0.1 mg/l of 4-nonylphenol showed similar changes as those exposed to 0.05 and 0.08 mg/l of 4-nonylphenol, however, degenerative changes, hypertrophied, karylyosis, blood sinusoids collapsation, apoptosis and vacuolated hepatocytes (Fig. 10, 11). Mitochondria were swollen with destructive cristae; electron dense materials appeared at the periphery of these mitochondria (em) (Fig. 9b, 10a, 11,a, b). Concentric whorly organization of rough endoplasmic reticulum (cw) with detached ribosomes were also seen (Fig. 11a). Other regions of the reticulum appeared as parallel cisternae with electron lucent cytoplasm between its cisterna also, circular arrays of RER

Histopathological Alterations in some Body Organs

following exposure to a variety of toxicants.

increased NP-induced anion gap.

and Al-Salahy, 2009).

pathway.

lamellae and oedema.

of Adult *Clarias gariepinus* (Burchell, 1822) Exposed to 4-Nonylphenol 169

4-nonylphenbol in this investigation may cause a drastic reduction in the respiratory surface area. However, very little is known about the toxic impact of 4-nonylphenol on the functional morphology of the gills. The present results indicated such toxic impacts. Increase in the number of mucous cells in gills of fishes exposed to 0.1 mgl-1 of 4 nonylphenol was recorded. It has been reported that the immediate morpho-pathological response of the gills to ambient xenobiotics is often manifested by a significant increase in the density of its mucous cells (Dutta, 1997, Hemalatha and Banerjee, 1997). The large quantity of mucous secretion acts as a defense mechanism against several toxic substances (Handy and Eddy, 1991; Mazon *et al.,* 1999). Similar to the findings of Dutta *et al.* (1996), the present results included many alterations such as increase in mucous and chloride cell number and size, necrosis, rupture of epithelium, desquamation, deformed secondary

According to Peuranen *et al.* (1994) any discontinuity of epithelial lining of the gill lead to a negative ion balance and to changes in the haematocrite and mean cellular haemoglobin values of the blood. The number of chloride cells increased in the present study and this is similar to the results of Parashar and Banerjee, (2002). They stated that the number of chloride cells in the epithelial linings of both primary lamellae and secondary lamellae of *Heteropneustes fossilis* increased significantly following exposure to lead nitrate solution. Dutta *et al.* (1996) summarized the increased number of chloride cells in the gills of fishes

Increased ion permeability and sodium efflux of gill epithelial cells due to ethoxylate nonylphenol were reported in rainbow trout (Pärt *et al.,* 1985). Similar results in the present work were recorded in the histology of gills under NP-stress and confirmed by the

The kidney of fishes receives the largest proportion of the post-branchial blood and therefore renal lesions might be expected to be good indicators of environmental pollution (Cengiz, 2006). Many studies used histological characteristics of kidney as an indicators of pollution especially nonylphenol (Srivastava *et al.,* 1990; Banerjee and Bhattacharya, 1994; Ortiz *et al.,* 2003; Cengiz, 2006). In the present work, histological changes in the kidney after exposure to 4- nonylphenol were necrosis, hypertrophy of glomerulus, degeneration and dissociation of renal tubules and Bowman's capsule, proliferation in the renal tubule and haemopoieatic tissue, shrinkage of glomerulus, pyknosis, dilated blood vessel, rupture of Bowman's capsule, and obliterated Bowman's space. Similar results were reported in fishes after exposure to other pollutants (Cengiz, 2006; Khidr and Mekkawy, 2008; Abdel-Tawab

From the results of the current study, it could be suggested that the exposure of adult catfish, Clarias gariepinus to sublethel doses of 4-nonylphenol caused moderate and severe damage to some organs such as gills, skin, kidney, and liver. These adverse effects of NP in gills, skin, kidney and liver were simultaneously correlated with sever biochemical, physiological changes in addition to endocrine disruption (Mekkawy et al., 2011; Mahmoud et al., 2011; Sayed et al., 2011) So, it is concluded that NP works as estrogenic and nonestrogenic factor leadings to general and specific metabolism disruption in different

were appeared (Fig. 10a, 11a). An increase in the number of lysosomes and fat drops were seen (Fig. 10b, 11b).
