Abstract: The heart,spleen,kidney,liver,intestine and gill from Sciaenops ocellatus infected with kidneyintumesce were pathologically analyzed by tissue slice and ultramicrocut electron microscopy techniques,so asto study the pathological changes of the tissues and the pathogenic mechanism of this disease.The anatomicalsymptoms of the diseased Sciaenops ocellatus are body surface ulceration,some lumps on the pterygiophore ofsome diseased fish,distinctly enlarged kidney (some 10 times as large as the normal one),enlarged liver,spleen and gallbladder, and white nodules on the viscera of some diseased fish.Histopathology shows that themain manifestations were typical granuloma,infiltration of large amount of inflammatory cells,rupture andnecrosis of the tubular wall of the renal tubule,parenchyma hyperemia and vacuolar degeneration of theparenchymal cells in the liver,and abundant diseased erythrocyte appeared in the spleen with hyperemia andfatty degeneration. Ultrastructure pathology shows serious apoptosis of the epithelial cells of the kidneyproximal tubule,sparse and ruptured brush border in the renal tubule,serious necrosis and blurredboundaries of the liver sell,and expansion of the splenic sinus of the spleen tissue,as well as abundantapoptosis cells of erythrocyte and lymphocytes. The results indicate that pathological changes widely occur intissue cells of the kidney intumesce Sciaenops ocellatus and cause serious damage to the body organs,whichmakes the infected fish lose normal physiological metabolism and died at last.

Key words: Sciaenops ocellatus, kidney intumesce, histopathology, ultrastructure