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Abstract：
Toxoplama gondii (Apicomplexa: Coccidia), an obligatory intracellular parasite with a unique capacity to invade virtually all nucleated cell type from warm-blooded vertebrate hosts. Despite the efficiency with which Toxoplasma enters its host cell, it remains unresolved if invasion occurs by direct penetration of the parasite or through phagocytosis. In the present work, electron microscopic study was designed to examine the entry process of Toxoplasma (RH strain) into macrophages and non phagocytic-host cells (Hela cells) and to observe the ultrastructure changes associated with intracellular parasitism. The results showed that both active invasion and phagocytosis were occurred and revealed that invasion is an ordered process that initiates with binding of the parasite at its apical end followed by tight-fitting invagination of the host cell membrane and a prominent constriction in the parasite at the site of penetration. The process ended by the professional parasitophorous vacuole that is distinct at the outset from those formed by phagocytosis in which once Toxoplasma triggered, phagocytic uptake can proceed by capture of the parasite within a loose fitting vacuole formed by localized membrane ruffling. The cytopathic effects of the parasite on macrophages and Hela cells were demonstrated within 5-15 h post-inoculation in the form of degenerative mitochondria, swelling Golgi apparatus and widening of endoplasmic reticulum indicating intracellular oedema. These changes were exaggerated and several cells were found dead after 48-72 h.
摘要：
弓形虫（顶孔虫：球虫），一种强制性的细胞内寄生虫，具有入侵温血脊椎动物宿主几乎所有有核细胞类型的独特能力。尽管弓形虫进入其宿主细胞的效率，如果通过寄生虫的直接渗透或通过吞噬作用发生入侵，则仍未解决。在目前的工作中,电子显微镜研究旨在检查弓形虫（RH株）进入巨噬细胞和非吞噬宿主细胞（Hela细胞）的过程，并观察与细胞内寄生相关的超微结构变化。结果表明，同时发生了主动入侵和吞噬作用，并揭示了入侵是一个有序的过程，该过程始于寄生虫在其顶端的结合，然后是宿主细胞膜的紧密配合内陷和寄生虫在体内的明显收缩。穿透部位。该过程以专业的寄生虫液泡结束，该液泡在一开始就与弓形虫触发的吞噬作用形成的液泡不同，吞噬摄取可以通过捕获寄生虫在局部膜起皱形成的松散合适的液泡内进行。在接种后5-15小时内，以变性线粒体的形式证明了寄生虫对巨噬细胞和Hela细胞的细胞病变作用，高尔基体肿胀和内质网增宽表明细胞内水肿。这些变化被夸大了，发现几个细胞在48-72小时后死亡。
