Galindo Mario, Gonzalez M Julieta, Galanti Norbel
Program of Cellular and Molecular Biology, Institute of Biomedical Sciences (ICBM), Faculty of Medicine, University of Chile, Casilla 70061, Correo 7, Santiago, Chile.
Biol Res. 2002;35(3-4):365-71. doi: 10.4067/s0716-97602002000300011.
Echinococcus granulosus is a parasitic platyhelminth that is responsible for cystic hydatid disease. From the inner, germinal layer of hydatid cysts protoscoleces are generated, which are are the infective forms to the dog. Systematic studies on the cell biology of E. granulosus protoscolex formation in natural infections are scarce and incomplete. In the present report we describe seven steps in the development of protoscoleces. Cellular buds formed by a clustering of cells emerge from the germinal layer of hydatid cysts. The buds elongate and the cells at their bases seem to diminish in number. Very early on a furrow appears in the elongated buds, delimiting anterior (scolex) and caudal (body) regions. Hooks are the first fully-differentiated structures formed at the apical region of the nascent scolex. In a more advanced stage, the scolex shows circular projections and depressions that develop into suckers. A cone can later be seen at the center of the hooks, the body is expanded and a structured neck is evident between the scolex and the body. During protoscolex development this parasitic form remains attached to the germinative layer through a stalk. When fully differentiated, the stalk is cut off and the infective protoscolex is now free in the hydatid fluid.
细粒棘球绦虫是一种寄生性扁虫，可引发囊型包虫病。从包虫囊肿的内层生发层产生原头蚴，原头蚴是对犬具有感染性的形态。关于自然感染中细粒棘球绦虫原头蚴形成的细胞生物学的系统性研究匮乏且不完整。在本报告中，我们描述了原头蚴发育的七个阶段。由细胞聚集形成的细胞芽从包虫囊肿的生发层长出。芽伸长，其基部的细胞数量似乎减少。在伸长的芽中很早就出现一条沟，划分出前部（头节）和尾部（身体）区域。钩是在新生头节顶端区域形成的首个完全分化的结构。在更高级阶段，头节呈现出圆形凸起和凹陷，这些会发育成吸盘。之后在钩的中心可见一个锥体，身体扩张，头节和身体之间有明显的结构化颈部。在原头蚴发育过程中，这种寄生形态通过一个柄附着在生发层上。当完全分化后，柄被切断，感染性原头蚴现在在包虫液中游离。
