Histopathological analysis of liver of the catfish Pimelodus maculatus in a tropical eutrophic reservoir from Southeastern Brazil

Araujo , Francisco GersonGomes, Iracema DavidNascimento, Aparecida Alves doSantos, Marcos Antonio José dosSales, Armando

We described liver tissues of the long-whiskered catfish Pimelodus maculatus using histological techniques through structures stained with hematoxylin and eosin. A total of 21 adult individuals were collected using gill nets during the winter of 2012, in a eutrophic reservoir in Southeastern Brazil. The main aim was to characterize the tissues and eventual changes, since this organ has a notable sensitivity to changes in altered aquatic systems. The liver contains the exocrine pancreas (hepatopancreas) that have pancreatic cells arranged around a branch of the portal vein. The hepatocytes are diffuse and arranged in cords. Normal liver of P. maculatus have a continuous compact field of weakly eosinophilic, rounded hepatocytes with scattered islands of connective tissue that enclose the bile ducts and blood vessels. The organization of exocrine pancreatic tissues is similar to the acinar morphology of many teleosts. Histopathological alterations in liver were evaluated semi-quantitatively and based on the severity of the lesions. The alterations in each organ were classified in progressive stages of damage to the tissue. Six types of liver alterations were found: 1) cytoplasmic vacuolization; 2) congestion; 3) inflammatory infiltrated; 4) infiltration of adipocytes; 5) steatosis; 6) granuloma. Incidence of melanomacrophage centers were observed in the liver. However, we cannot directly associate such changes with the eutrophic conditions of the reservoir, because we have no available reference area to compare. These findings are a baseline contribution, which enables comparisons with similar fish species in other tropical aquatic systems in further studies.(AU)

1. hepatic alterations
2. freshwater fish
3. Liver
4. reservoirs