军曹鱼淋巴囊肿的病理学研究

应用病理组织学和电镜方法,对患疑似淋巴囊肿病的军曹鱼(Rachycentron canadum)的各器官进行观察.结果表明,患病军曹鱼的皮肤囊肿组织由一些淋巴囊肿细胞集合体组成,这些囊肿细胞排列紧密,直径为10～150 μm,细胞呈圆形、锥形不规则状;细胞外有一层厚的囊膜;细胞质内散布有大量的嗜碱性包涵体,且多数集中在细胞的边缘部分;电镜观察到囊肿细胞质中有大量二十面体的病毒粒子,病毒颗粒直径220 nm.据此确认该病为病毒性淋巴囊肿病.其他器官主要组织病理学变化有:在心脏、肝脏、脾脏和头肾中也存在囊肿细胞,心肌纤维水肿;肾间质淋巴细胞增生,巨噬中心出现,肾小管上皮细胞变性和坏死;脾淋巴细胞增生,脾髓质出血;肝脂肪变性;鳃上皮肿胀.根据观察结果可以认为,该病毒不仅损伤鱼的皮肤,致使病鱼外观异样而严重影响其商品价值,而且对鱼的内脏和免疫器官也造成严重的致命损伤.

Histopathological study on lymphocystis disease of Rachycentron canadum

The cage-culture of cobia, Rachycentron canadum, was developed rapidly in southern China in recent years. In 2005, a similar lymphocystis disease of cage-cultured cobia broke out in Guangdong Province, China, and papilloma-like tissues appeared in the body and fin of diseased fish. In order to diagnose the disease of Rachycentron canadum suspected of lymphocystis disease, the histopathologic changes in the fish and the morphology of the virus particles were observed under optic and electronic microscope. The results showed that the papilloma tissues in the derm of the Rachycentron canadum were actually constituted by many lymphocystis cells which aggregated tightly. The size of the lymphocystis cells varied and ranged from 10 to 150 tan in diameter. Infected cells were round, cone-shaped or anomalous. A thick enveloped membrane layed in outside of lymphocystis cell. A lot of basophilic inclusion bodies existed in the lymphocystis cell and most of them were located on the edge of the cytoplasm. Under electronic microscope, there were a lot of particles icosahedron-shaped in the cytoplasm of infected cells and the size of the viruses was approximately 220 nm in diameter. In addition, swollen lymphocystis cells were observed in heart, liver, spleen and head kidney under optic microscope. According to the results above, the disease was diagnosed as lymphocystis disease. The main histopathologic changes of the other organs under optic microscope show that the damage to heart presents as cardiac cell vacuolar degeneration and swelling of cardiac muscle fiber; lymphocytosis and melanin-macrophage centers present in interrenal tissue and spleen;denaturalization and necrosis emerge in renal tubule epithelial cell; livers shows fatty degeneration of hepatocyte; and the gill lamellar epithelial cells are swollen.