文蛤外套膜“肥大症”的组织病理学研究

Study on Histopathology of the Cultured Clam Meretirx meretrix Suffered from the "Mantle Hypertrophy Disease"

2003年3～5月,山东莱州某养殖场部分养殖文蛤(Meretrix meretrix Linnaeus)出现外套膜异常肥大现象.组织病理学研究显示,患病贝外套膜、水管、鳃、足等器官组织内粘液细胞增多,水管两侧的外套膜结缔组织中粘液细胞增生尤为明显.同时,患病贝各器官组织还呈现出不同程度的病理学变化,主要表现为组织结构紊乱,上皮细胞肿胀、脱落,生殖细胞滞育、退化,肌纤维变形、溶解,血细胞增生并诱发炎症反应等.在患病贝体内主要观察到3种寄生性原生动物,分别为缘毛类纤毛虫、粘孢子虫及1种顶复门类'孢子虫'.纤毛虫数量较少,主要寄生于鳃表面;粘孢子虫数量较多,寄生在水管、外套膜、鳃、性腺、消化盲囊、血淋巴等器官组织中,以水管结缔组织内数量最多;而顶复门类'孢子虫'主要发现于消化道结缔组织中.组织病理学研究表明,这3种寄生虫可能是病害发生的重要原因.

In 2003, from March to May, marine clams Meretrix meretrix suffering from “mantle hypertrophy disease” were found in the Laizhou district of Shandong Province. The main symptoms of the diseased clams were corpulent and swollen mantles, increased mucus. The histopathology characters were studied by histological methods. The characters showed that the mucus cells increased abnormally in tissues of gills, mantles, feet, and especially the connective tissues of mantles near the siphons that were filled with abnormally increased mucus cells, which resulted in mantle＇s corpulence. Moreover, many other pathological changes were found in the tissue of diseased clams, e.g., the tissue structure was disorganized, the epithelial cells swelled and detached from the wall, the germinal cells were growing slowly and even degraded, the muscle fibers were swollen and dissolved, and the hemocytes were hyperplastic and induced an inflammation etc.. At least three kinds of parasitic protozans were found in the body of diseased clams, one of them was Peritrichous ciliate, the other two were Myxospozoa and Epicomplexa. The ciliate lay mostly in ectoparasite of the gill and was less in number, the Myxospozoa was found in such tissues as mantle, gill, digestive tracts, digestive diverticulum, gonad, hemlymph and siphons in which a great deal of sporozan parasized, and the Epicomplexa was mainly found in the connective tissue of the digestive tract.