Histological and histometric evaluation of the liver in Astyanax bimaculatus (Teleostei: Characidae), exposed to different concentrations of an organochlorine insecticide

To investigate possible morphological changes to the liver tissue of lambaris, Astyanax bimaculatus (Linnaeus, 1758), females were exposed to treatments of sublethal concentrations of the insecticide Thiodan® for 96 hr. Treatments included three sublethal concentrations of 1.15, 2.3, and 5.6 μg L−1 of Thiodan® and a control group without insecticide. The action of Thiodan® at sublethal concentrations did not affect the morphological structure of the liver as a whole, but changes in isolated locations of the hepatic parenchyma were observed. Glycogen depletion, nuclear and cytoplasmic deformation, nuclear and cytoplasmic hypertrophy, hyperemia, and cellular degeneration in liver cells at the different concentrations studied were recorded. These observed changes in the livers were greater in groups exposed to Thiodan® in comparison to the control group. Furthermore, there was a change in the diameter of the nuclei and cytoplasm of hepatocytes in the different treatments. The groups exposed to Thiodan® also exhibited a larger number of hepatocyte nuclei and a reduction in the amount of cytoplasm. We conclude that for the exposure period and concentrations of Thiodan® analyzed, the morphology of hepatic tissue had a cellular adaptive response