养殖文蛤体内寄生的一种吸虫幼虫及宿主组织病理学

作为文蛤吸虫病害研究的基础资料，报道了寄生在文蛤体内的1种复殖吸虫幼虫的形态结构及宿主由此所产生的组织病理学变化。研究表明：该吸虫分别为咆蚴和尾蚴。咆蚴圆筒形，内含不同发育阶段的尾蚴。成熟尾蚴体成扁平舌状，具有口吸盘、腹吸盘，1对眼点和1条细长无刺的尾巴。该吸虫主要侵占生殖腺，少部分幼虫进入附近的消化盲囊、鳃、肾等部位。轻微感染者，生殖滤泡萎缩，生殖细胞发育滞后；严重感染的宿主，生殖腺完全被侵占并耗尽。消化盲囊、鳃、肾等器官组织也因幼虫感染呈现不同程度的病理学变化；严重者上皮细胞水肿或脱落，肌肉组织结构紊乱或溶解等。本工作同时显示，吸虫寄生可诱发宿主血淋巴细胞大量增生，并产生凝集、组织浸润及形成包囊等免疫反应。

A Treamatode Larva Parasitized in Cultured Marine Bivalve, Meretrix meretrix Linnaeus and Its Histopathology

Meretrix meretrix Linnaeus is one of the most important cultured molluscs in China, which has suffered a series of diseases and high mortalities in recent years. In spring 2003, sporocysts and their cerecarias of an unknown digenea were observed in cultured Meretrix meretrix from Laizhou, Shangdong Province. The main symptom in the infected clams was that the visceral mass became thin and dim, the mucus increased and the surface of the shell lacked luster. This study reports the morphological characteristics of the larva of the treamatode and histopathology of the host induced. The well developed cerecaria consists of two parts, the body and the tail. The body is flat and ligulate, with suckers, a pair of eyepoints, and the tail is slender and without any thorn. Histological examination reveals that most larvae occupied the gonad of the clam, relatively fewer appeared in other organs, such as the digestive diverticulum, gills, kidney etc. It not only harmed the tissues parasitized by the parasites, but also caused the other organs to debilite in various degrees. In heavy infestations, the gonad was completely destroyed and replaced by mass of larval treamatodes. Other organs showed pathological changes, e.g. the epithelial cells swelled, some were sloughed off the wall of the digestive tract, digestive diverticulum and gills. The structure of muscular tissue became irregularly arranged or dissolved, etc. The host hemocytes were seen congregated round the the parasites and formed the structure of capsules, and inflammations were induced in the host by parasitization of the treamatode. Our results indicated that treamatodes induced severe demolishmtent in its host. In the end, all of the essential organs broke down, causeing the death of the host.