在细粒棘球绦虫一些原发性包虫囊内存在子囊在中间宿主绵羊和人中是常见现象,只在马中罕有报告。但对这些结构的来源则意见不一。通常的假定是:在原发性包虫囊内原头节因囊的发育侍到抑制,生发层部分反折入囊腔而形成子囊。在这些假定中忽略的主要一点是子囊的存在与原发性囊的损伤 The presence of ascus in some primary hydatid cysts of the Echinococcus granulosus is common in intermediate host sheep and humans and is rarely reported in horses. However, the sources of these structures are mixed. The usual assumption is that in the primary hydatid cyst, the protuberant protuberance is inhibited by the development of the sac and the germinal layer partially folds into the cyst and forms the ascus. The main point to ignore in these assumptions is the presence of the ascus and the damage of the primary capsule