美国鲥鱼内脏结节病的组织病理学观察

Histopathological observation of visceral sarcoidosis in Alosa sapidissima

为探究美国鲥鱼内脏结节病的病因和病理,本实验从患内脏结节病的美国鲥鱼体内剖离出肝、脾和肾等内脏器官组织,通过对病鱼样品H.E染色、马松染色和抗酸杆菌染色,并结合亚显微结构观察对病变组织、细胞以及疑似病原菌进行分析。病鱼的临床症状表现为体表多处损伤,鳞片下出血,腹部膨大,肛门出血。病理解剖见腹腔内含大量积水,肝、肾和脾脏表面有大量白色结节,肝脏呈深红色,多处破裂出血,肾脏表面附着大量白色纤维样病变,失去原有颜色和结构,脾脏呈深褐色,肠壁充血,未见其他器官组织有结节分布。组织病理观察结果表明:显微结构所见肝、脾和肾组织病变为肉芽肿,且又大又多。肉芽肿中心由坏死的组织碎片和聚生菌体组成,外围有大量的炎性细胞浸润,包膜由纤维组织构成。肝脏组织内含大量空泡为脂肪变性;肾组织内肾小管腔破裂分解,肾间质出现大面积组织坏死;脾组织间充斥大量红细胞。其他内脏组织内未见肉芽肿。抗酸染色和亚显微结构观察证实滋生在肉芽肿内的细菌为一种短杆菌。由此得出,肝、脾和肾组织由于病原菌感染形成大量肉芽肿,导致脏器产生大量的结节,最终出现器官功能低下或衰竭导致鱼体死亡。

In order to investigate the etiology and pathology of visceral sarcoidosis in American shad(Alosa sapidissima),the liver,spleen,kidney and other organs of diseased shad were isolated,H.E routine staining,Masson staining and Ziehl-Neelsen staining,combined with microstructure were used for observing and analysing diseased tissues and cells as well as pathogenic bacteria.The sick shad exhibited the clinical symptoms that were multiple injuries on the body surface,bleeding under the scales,slightly enlarged abdomen and bleeding from the anus.Pathological anatomy revealed that the abdominal cavity was filled with a large amount of blood mixed with ascites,and there were a great number of white nodules in internal organs such as liver,kidney and spleen,with multiple ruptures and bleeding.In details,the liver surface was dark red.The kidney surface was covered with numerous white fibrous lesions,and the original color and structure of the kidney were changed.The spleen was deep black and intestines were bleeding.Nodules were not seen in other organs.Histopathological analysis showed that many granulomas emerged in the liver,spleen,and kidney seriously.The granuloma center consisted of necrotic tissue fragments and concomitant bacteria,the periphery of granuloma was infiltrated with a large number of inflammatory cells,and the envelope was composed of fibrous tissue.Liver tissue was filled with many vacuoles,which were steatosis.Renal tubules in kidney tissue were ruptured and decomposed,large area of tissue necrosis and disintegration appeared in renal interstitial tissue.Spleen tissue was filled with a large proportion of red blood cells.No granuloma was found in other internal organs.Observation with Ziehl-Neelsen and submicroscopic structure confirmed that the bacteria growing in the tissues was proved to be Bacillus brevis.Therefore,a large number of granulomas emerged in liver,spleen,and kidney tissues because of pathogens infection,which led to numerous nodules in the organs.Eventually,organs showed dysfunction and exhaustion,then resulted in death of disabled fish.