**2.2 4-nonylphenol**

164 Zoology

to cause histopathological changes in the germ and Sertoli cells of the male eelpot (Christiansen et al. 1998). The skin of fish is continuously exposed to and in direct contact with the environment pollutants such as NP. Histological changes in skin of rainbow trout with mucosomes in goblet cells were recorded after exposure to 10 µg/l of 4-nonylphenol. Several studies demonstrated the high susceptibility of skin to environmental pollutant impacts (Burkhardt-Holm et al. 1997; Iger et al. 1995; Shephard, 1994). Burkhardt-Holm et al. (1997) hypothesized that in trout, xenobiotic estrogens might affect the skin, like natural

In trout species, nonylphenol was found to accumulate in the liver, gill, skin, gut, fat, and kidney tissue (Ahel et al. 1993; Coldham et al. 1998; Lewis and Lech, 1996). So that, 4 nonylphenol may affects those organs in corresponding with its impacts on reproductive ones. Most of NP studies revealed sever effects on the liver and gonads of fish tissues (Christiansen et al. 1998; Jobling et al. 1996; Lech et al. 1996) and the corresponding metabolism. The liver is important in many aspects of nutrition, including lipid and carbohydrates storage and alterations in liver structure may be useful as biomarker that indicate prior exposure to environmental stressors (Hinton and laurén, 1990). Stressorsassociated alterations of hepatocytes may be found in the nucleus or cytoplasm or both (Marchand et al. 2008). Malik and Hodgson, (2002) reported that the liver plays a major role in complex enzymatic processes of thyroid hormones conversion. So, liver dysfunction and disease affects thyroid hormone metabolism. Although gills are not only the prime organs for gaseous exchange, they perform several other physiological functions including osmoregulation and excretion. Parashar and Banerjee, (2002) reported that changes in environmental parameters often damage this delicate vital organ which has direct contact with aquatic environment. Many studies demonstrated that increased concentrations of different pollutants including several heavy metals seriously damage the gills of teleostean

African catfish (*Clarias gariepinus*), an omnivore freshwater fish, is a popular delicacy relished throughout tropical Africa (Nguyen and Janssen, 2002) due to fast growth rate, high stocking-density capacities, high consumer acceptability and high resistance to poor water quality and oxygen depletion (Adewolu et al. 2008; Akinwole and Faturoti, 2007; Karami et al. 2010). Because it is a prominent culture species (Adeyemo, 2008), the African catfish has

The present work is an extension of previous studies of the present authors (Mekkawy et al., 2011; Mahmoud et al., 2011; Sayed et al., 2011) to determine to what extent the histopathological variations in some organs of the adult catfish, *Clarias gareipinus* (Burchell, 1822) are simultaneously correlated with biochemical and physiological NP-induced

Specimens of adult catfish *C. gariepinus* were collected from the River Nile at Assiut and then were transported to Fish Biology Laboratory of Zoology Department, Faculty of Science, Assiut University. The fish (500–1200 g) were fed on a commercial pellet diet (3% of body weight per day) and kept together in 100 l rectangular tanks containing tap water

been used in many fundamental experimental researches (Mahmoud et al., 2009).

estrogens, via the steroid receptor.

fish (Dutta et al. 1996; Wendelaar Bonga, 1997)).

changes especially in respect with endocrine disruption.

**2. Materials and methods** 

**2.1 Specimen collection** 

4-Nonylphenol was obtained from Sigma- Aldrich (Schnelldrof, Germany)
