叶巢外睾吸虫幼虫期在湖北钉螺体内的发育及生活史研究

STUDIES ON THE LIFE CYCLE OF EXORCHIS OVARIOLOBULARIS AND ITS DEVELOPMENT IN ONCOMELANIA HUPENSIS

叶巢外睾吸虫（ＥｘｏｒｃｈｉｓｏｖａｒｉｏｌｏｂｕｌａｒｉｓＣａｏ，１９９０）是寄生在福建闽江口的鲶鱼（Ｐａｒａｓｉｌｕｒｕｓａｓｏｔｕｓ）的肠道中。在闽江两岸的图氏窄口螺（ＳｔｅｎｏｔｈｙｒａｔｏｕｃｈｅａｎａＨｅｕｄｅ）虽曾见到此类吸虫的幼虫期，但其生活史未经研究。本文报告在实验室内用湖北钉螺（Ｏｎｃｏｍｅｌａｎｉａｈｕｐｅｎｓｉｓ）作为实验贝类宿主所进行的感染试验，并观察了本吸虫的全程生活史各阶段发育的情况。此类吸虫毛蚴到贝类宿主体内只经过一代胞蚴，一代雷蚴和尾蚴的发育，而后期尾蚴在作为第二中间宿主的小鱼体中发育形成囊蚴。全程生活史从秋天到翌年初夏历时需半年。

The adults of Exorchis ovariolobularis were obtained from the intestine of Parasilurus asotus occurring in Min River,Fuzhou.Its natural molluscan intermediate host may be Stenothyra toucheana which usually inhabits on the sides of Min River in Fuzhou.The life cycle of E.ovariolobularis was established experimentally in our laboratory and all developing stages were described. Eggs were fully embryonated after being laid from adult and were swallowed by the experimental molluscan host, Oncomelania hupensis. The miracidia of E.ovariolobularis penetrated into the intestinal wall of snails and transformed into small embryos with germinal cells.Sporocysts developed outside the intestine in the digestive gland of snail.Only one generation of sporocyst occurs in its life history .Sporocyst of Exorchis ovariolobularis gave rise to rediae which spread from sporocyst to the spaces of digestive gland and parenchyma of snails.There was only one generation of redia too.Redia gave rise to cercariae.Cercariae emerged from Oncomelania hupensis 210 days after the eggs of E.ovariolobularis had been eaten by snails.Cercariae penetrated and encysted in the tissue of the experimental hosts,goldfishes. Exorchis ovariolobularis is separated from its closely related species, E.dongtinghuensis ,by the structure of the excretory canals of cercaria,and in having a Y shaped excretory vesicle in metacercaria of E.ovariolobularis ,which is different from the V shaped of that in E.dongtinghuensis.