中文摘要：

目的单独感染外睾吸虫的湖北钉螺，螺体分泌物和血淋巴细胞剧烈增加；螺体表分泌物含大小不等颗粒及晶体状物，体内分泌物为金黄色或褐色小颗粒，各颗粒团附近均有极小细胞核。双重感染外睾吸虫和日本血吸虫的钉螺，体内外分泌物和血淋巴细胞等产物同样大量产生；体内分泌物颗粒及其附近小细胞核、3种血淋巴细胞及副腺细胞，出现在血吸虫幼虫周围并进入虫体内；所有血吸虫幼虫结构异常，停止发育并死亡。阴性钉螺和单独感染日本血吸虫的钉螺，它们体内外分泌物及血淋巴细胞的数量均少；分泌物颗粒和血淋巴细胞虽有在血吸虫幼虫附近，但都没有进入虫体内。

英文摘要：

The objective was to understand the reactions of snail secretions and lymphocytes to the larval Schistosoma japonicum in Oncomelania hupensis snails preinfected with Exorchis sp. and they were compared with the conditions of negative O. hupensis snails, snails singly infected with Exorchis, and singly infected with S. japonicum. In the snails at 12-105 d after infection with Exorchis, snail secretions and lymphocytes increased much. Those situations were also found in the O. hupensis snails dual infected with Exorchis and S. japonicurn. Thick secretion with granular and crystal structure on snail body surface and in snail inner tissue were much small secretive granules with some small cell nuclei, lymphocyte with spherical nu- clei of 3 varying sizes and accessory gland cells, some of which were found in the bodies of all abnormal S. japonicum larvae. In the negative O. hupensis and snails singly infected by S. japonicum the secretions and lymphocytes were very few. Neither secretive granule nor lymphocytes was found in any bodies of S. japonicum larvae in （9. hupensis snail singly infected by S. japonicurn.