Histopathological evaluation of the spleen, heart, and brain of the tilapia Oreochromis niloticus (Linnaeus, 1758) exposed to mercury chloride

Abstract

The objective of this investigation was to assess the effects of the mercury chloride toxicity on the histological evidence of tilapia Oreochromis niloticus. The spleen, heart, and brain were investigated. Immature tilapia was used (27.13 ± 4.67 g and 12.44 ± 0.84 cm). The fishes (n=102) were exposed to three concentrations of mercury chloride (HgCl₂): C1=0.02 mg L^-1, C2=0.002 mg L^-1, and C3=0.0002 mg L^-1, plus the control group. Samples were collected after 3, 7, 10 and 14 days of exposure. The center of melanomacrophages of the spleen showed hyperplasia and hypertrofia, being proportional to the tested concentrations. However, in brain and heart the alterations were not relevant when compared to those observed in the control group.