Effect of Aeromonas hydrophila in the tissue structure of liver and immune organs in Acanthopagrus latus

Bacterial diseases in cultured fish are considering the main problem with aquaculture system in world. Aeromonas hydrophila is an opportunist pathogen in fish and responsible for wide range of fish diseases. The aim of this study was to assess the structure of tissue liver, spleen and head kidney in Yellow fin Sea bream Acanthopagrus latus, under exposure to the Aeromonas hydrophila by immersion way. In this regard, 90 A. latus were exposed to sub lethal concentrations of Aeromonas hydrophila (103,106CFU/ml) for 3 weeks. The samples tissues were taken from the liver, spleen and head kidney after fish dissection and were fixed 10% neutral buffered formalin. Five-Six micrometer thick sections were obtained and were stained in hematoxylin-eosin for examination in light microscopy. According to the results, the pathological changes in the liver included vacuolation of hepatocytes, nuclear hypertrophy, focal necrosis, dilation of sinusoid and diss spaces, melanomacrophages aggregates and hemorrhage. According to the results, the pathological changes in the spleen included an increase in melano-macrophage aggregates in the all samples. The histopathological changes in the head kidney included an increase in melano-macrophage aggregates, hemorrhage, lifting of tubular basement membrane and Empty spaces between cells. The results of the present study showed that the alternations of liver and immune organs tissue structure and function in Achantopagrus latus caused by the A. hydrophila infection.