![]() ![]() The animals were exposed to the considered safe levels of lithium (2.5 mg L⁻¹) and selenium (10 μg L⁻¹), both, isolated and mixed. The assay was carried out over 21 days with two periods of sampling (after 7 and 21 days) to assess the effects of exposure over time. The immunologic responses were assessed by the quantification of melanomacrophage centres (MMCs) the histopathologic evaluation of the liver sections was also performed. To do so, we assessed the metabolic, immunologic, and histopathologic alterations in liver samples of American bullfrog (Lithobates catesbeianus), at the premetamorphic stage, through biomarkers indicative of general energetic status, i.e., glucose, lipid, and protein metabolism using biochemical and histochemical approaches. Considering the threat that these animals have been suffering in tropical regions, the present study tested if the Brazilian legislation, concerning the permissive levels of lithium and selenium in water bodies and effluents, warrants the protection of aquatic life. The presence of chemicals and the destruction of freshwater habitats have been addressed as one of the reasons for the decline in the amphibians’ populations worldwide. Free-living bullfrogs feed on proteins of better biological value, derived from animals preyed in the natural environment. Morphologically, unlike the livers of animals reared on farms, the livers of free-living animals did not show any evidence of protein-mineral deficiency, characterized by cytoplasmic vacuolation and a larger number of melanomacrophages, suggesting greater aggression to the liver parenchyma, probably due to environmental toxicity. ![]() In the farmed bullfrogs, cytoplasmic rarefaction was normal. Additionally, hepatocytes showed cytoplasmic eosinophilia and some showed nuclear hypertrophy and presence of microvesicular steatosis small foci of infiltrates of mononuclear cells were observed in some samples, as well as a thicker capsule. Marked blood congestion and even hemorrhage and a large number of melanomacrophages were observed in most of the livers from free-living bullfrogs. Thirty liver samples were collected from young and adult bullfrogs in the states of Minas Gerais and Rio de Janeiro, Brazil. ![]() The objective of this study was to compare the histopathological aspects of the liver of free-living and farmed bullfrogs (Lithobates catesbeianus). ![]()
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