Bannister L H, Dluzewski A R
Department of Anatomy, United Medical School, Guy's Hospital, London, UK.
Blood Cells. 1990;16(2-3):257-92; discussion 293-7.
Within the circulation, the invasive stage of Plasmodium is the merozoite, a small elliptical cell. Electron microscopy shows that the merozoite can attach reversibly to erythrocytes by its adhesive coat, then form a close, irreversible contact by its apical end, triggering secretion from membranous vesicles (rhoptries and micronemes) on to the erythrocyte membrane. This causes the erythrocyte membrane to invaginate and the merozoite then becomes enclosed within a cavity lined by interiorized membrane. In uninfected erythrocytes, the surface membrane consists of a lipid bilayer in which lie various integral membrane proteins and glycoproteins, associated at their cytoplasmic ends with a network of other proteins constituting the membrane skeleton. There is much evidence that during invasion the membrane proteins and skeleton are removed from the invaginated membrane. There are also ultrastructural data suggesting that the rhoptries are able to generate membrane-like materials, which are inserted into the erythrocyte membrane to cause its inward expansion. Further expansion may be induced by the liberation of parasite secretions from another set of organelles (microspheres) released after the first stage of invasion.
在血液循环中，疟原虫的侵入阶段是裂殖子，它是一种小的椭圆形细胞。电子显微镜显示，裂殖子可通过其粘附外衣可逆地附着于红细胞，然后通过其顶端形成紧密、不可逆的接触，触发膜性小泡（棒状体和微线体）向红细胞膜分泌。这导致红细胞膜内陷，然后裂殖子被包裹在由内化膜衬里的腔内。在未感染的红细胞中，表面膜由脂质双层组成，其中含有各种整合膜蛋白和糖蛋白，它们在细胞质末端与构成膜骨架的其他蛋白质网络相连。有很多证据表明，在侵入过程中，膜蛋白和骨架从内陷膜中被去除。也有超微结构数据表明，棒状体能够产生类似膜的物质，这些物质被插入红细胞膜以使其向内扩张。进一步的扩张可能由入侵第一阶段后释放的另一组细胞器（微球）释放的寄生虫分泌物所诱导。
