Histopathological and histochemical studies of gills in AGD infected Barbus sharpeyi

Objective: Amoebic gill disease (AGD) is a serious important parasitic disease of fish culture industry elsewhere in the world which occurs following prolonged periods of high water temperature. The aim of the present study was to investigate the histopathological and histochemical changes of gills in Barbus sharpeyi infected with AGD. Method & Materials: This study was carried out on 40 mature B. sharpeyi in cold (January) and warm (August) seasons. After biometrical study, gross gill scores were recorded for each fish and the samples were taken from dorsal, middle and ventral part of gill arches on either side. For histopathological and histochemical studies, tissues were fixed in Bouin’s solution and then were processed by routine and standard paraffin embedding method. The sections were stained with H&E, PAS and two pH of alcian blue. Results & Conclusion: The results showed that most gross changes of infected gills were presence of scattered opaque mucoid patches upon the gills and excessive mucus production. Percent of infection was more in cold season. Histopathological studies indicated that the fusion of the adjacent secondary lamella was observed in the most cases but entire fusion of primary lamella was not seen generally. Some histopathological changes such as thickening of the lamella epithelium, hyperplasia and hypertrophy of surface epithelial cells, lamellar oedema, reduction in chloride cell abundance, increase in mucous cell number of the epithelium congestion and hyperemia of lamellae were recognized. Pathological changes were defined and classified as sever to week. Enlargement and hyperplasia of goblet cells especially around the invading amoebae and accumulation of abnormal amounts of mucous material in goblet cells was a dominant lesion. Large vacuoles containing of inflammatory cells and / or amoebae were seen in the hyperplastic gill lamellae. The histochemical studies revealed that nature of mucous in goblet cells changed in localized sites of amoebic infection. An increase in neutral and carboxylated mucins were observed in these regions.

کلیدواژه ها:

AGD ، Histopathology ، Histochemistry ، gill ، Barbus sharpeyi