Abstract: Snails are the intermediate host of Schistosoma and they play an important role in the transmission of schistosomia? sis. The snails in different areas present various susceptibilities，which are related to the different hemocytes in the snails. There is not a common standard in the classification of hemocytes，and generally the hemocytes are divided into two categories：a granulo? cyte and a hyalinocyte. The granulocyte plays an important role in immunization，while hyalinocyte shows a less effect. Besides， soluble factors may also play a role in immunization.

Key words: Schistosomiasis； Snail；Susceptibility； Hemocyte； Granulocyte；Hyalinocyte

摘要： 螺类是血吸虫的中间宿主， 对血吸虫病流行起着重要的作用。不同地域的螺类对血吸虫具有不同的易感性， 这 可能与螺体内淋巴细胞的不同有关。螺类淋巴细胞的分类尚未有统一标准， 通常按淋巴细胞胞内有无颗粒分为颗粒细胞 和透明细胞。颗粒细胞在免疫作用中发挥重要作用， 而透明细胞的免疫作用较小。此外， 螺类组织分泌的可溶性因子也 有可能发挥一定的免疫调节作用。

关键词: 血吸虫病； 螺类； 易感性； 淋巴细胞； 颗粒细胞； 透明细胞