Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Cell Microbiol. 2011 Dec;13(12):1920-32. doi: 10.1111/j.1462-5822.2011.01681.x. Epub 2011 Sep 22.
The encystation process is a key step in Toxoplasma gondii life cycle, allowing the parasite to escape from the host immune system and the transmission among the hosts. A detailed characterization of the formation and structure of the cyst stage is essential for a better knowledge of toxoplasmosis. Here we isolated cysts from mice brains and analysed the cyst wall structure and cyst matrix organization using different electron microscopy techniques. Images obtained showed that the cyst wall presented a filamentous aspect, with circular openings on its surface. The filaments were organized in two layers: a compact one, facing the exterior of the whole cyst and a more loosen one, facing the matrix. Within the cyst wall, we observed tubules and a large number of vesicles. The cyst matrix presented vesicles of different sizes and tubules, which were organized in a network connecting the bradyzoites to each other and to the cyst wall. Large vesicles, with a granular material in their lumen of glycidic nature were observed. Similar vesicles were also found associated with the posterior pole of the bradyzoites and in proximity to the cyst wall.
囊包形成过程是刚地弓形虫生活史中的一个关键步骤，使寄生虫能够逃避宿主的免疫系统并在宿主之间传播。详细描述囊包阶段的形成和结构对于更好地了解弓形体病至关重要。在这里，我们从老鼠大脑中分离出囊包，并使用不同的电子显微镜技术分析囊包壁结构和囊基质组织。获得的图像显示，囊包壁呈丝状，表面有圆形开口。这些丝状物组织成两层：一层紧密，朝向整个囊包的外部，另一层较疏松，朝向基质。在囊包壁内，我们观察到小管和大量囊泡。囊基质呈现出不同大小的囊泡和小管，它们组织成一个网络，将缓殖子彼此连接，并与囊包壁连接。观察到大的囊泡，其腔内有颗粒状物质，具有糖基性质。还观察到类似的囊泡与缓殖子的后极和靠近囊包壁的地方有关联。
