Morphological parameters of hepatocytes in the European mole (Talpa europaea) and herb field mouse (Sylvaemus uralensis) under industrial pollution: Qualitative and quantitative assessment.

Abstract

Morphological alterations of cells and tissues usually occur in biological organisms exposed to environmental contaminants, thereby acting as a biomarker of environmental pollution, thus, making this study highly pertinent. The effect of industrial pollution on the qualitativeand quantitative morphological parameters of hepatocytes (through histological analysis andcytomorphometry) was studied in two contrasting species of small mammals (Talpa europaea and Sylvaemus uralensis), taking into account the animal age (young and adult groups) and liver concentrations of heavy metals (Cu, Zn, Cd, Pb). Studies were performed in the regions exposed to emissions from two currently operating copper smelters: Middle Ural Copper Smelter (Middle Urals, T. europaea catching area) and Karabash Copper Smelter (Southern Urals, S. uralensis catching area). Seven morphometric parameters of hepatocytes were measured, of which two key parameters were selected by the method of principal components-the cell packing density and nuclear-cytoplasmic ratio (N/C). It was found that cell packing density in T. europaea from the impact zone decreased relative to the background area in young animals. At the same time, the differences in this parameter between the age groups from the background zone were leveled in the impact area of catching. The N/C ratio in T. europaea hepatocytes showed no correlation with either animal age or site of capture (background or impact area). In S. uralensis, both parameters, even taking into account the age, were found to be insensitive to indicate an effect of industrial pollution. Dystrophic changes (tested through histological analysis) in the liver tissue were revealed in all animal groups, but their frequency did not depend on any of the factors (age, zone) as well as the level of accumulation of toxicheavy metals (Cd, Pb). Morphometric parameters of hepatocytes have proved to be more reliable indicators of pollution, compared to the frequency of liver histopathology, due to lower subjectivity in their evaluation.