الملخص

The present work was aimed to evaluate the histopathological changes in hepatic tissue of Nile tilapia (Oreochromis niloticus) isolated from various sources of water in the Kerbala Governorate, Iraq. A total of 40 fish specimens were collected from several sites in the Kerbala Governorate representing a variety of environmental conditions. Liver samples were carefully dissected and fixed in 10 % neutral buffered formalin and processed by routine histological techniques used for microscopic examination. Tissue specimens were histologically diagnosed with Harris haematoxylin with eosin (H&E) and Periodic Acid–Schiff (PAS) stained. The results of the histological comparison concluded that all experimental groups presented histologically abnormal liver tissues, highlighting the great influence of the environment on liver integrity and consequently on fishes’ health. The most significant changes were in portal and parenchymal fibrosis with an increase in connective tissue growth. The distinct hepatocellular alterations recorded were disruption of hepatic cord architecture with vacuolar and hydropic degeneration. Vascular changes were there as well with either constriction or dilation of hepatic sinusoids and infiltration of proteinaceous material. Histochemical evaluation demonstrated a higher concentration of glycosaminoglycans (GAGs) in the hepatic parenchyma. Likewise, inflammatory responses were observed with an increased infiltration of fibroblasts and melano-macrophage cells (MMCs). The degree of liver changes was different among the studied groups from moderate degenerative and fibrotic changes to severe cellular damage and necrosis, suggesting a progressive pattern of liver damage depending on the environmental conditions. These results emphasise the relevance of hepatic histological alterations as reliable biomarkers in the assessment of aquatic pollution and general environmental health status.