Structure and life cycle.

Plasmodium species, as members of Apicomplexa, share many common morphological features. Each of the developmental stages in the life cycle of malaria parasites exhibits a remarkable conservation and distinct patterns of structural organization [1, 2]. These conservations are supposed to have originated in the special adaptation to the tissues and/or cells in the different hosts of malaria parasites. As the technology of electron microscopy has improved, more detailed electron microscopic observations of the various stages of malaria parasites have been carried out and greatly advanced our knowledge of the life cycle and the fine structure of malaria parasites. Although the significance of the morphological changes is not fully understood, the introduction of the techniques of immunoelectron microscopy to the field of malaria parasites [3] has helped us in the meaningful and dynamic analysis of parasite morphology and cell biology, and our knowledge of the subcellular localization of malaria antigens and their functions in specific parasite organelles has been accumulated. Structural, biochemical and molecular biological aspects are different among the complex cycle comprising the erythrocytic schizogony, mosquito stages, and preerythrocytic (exoerythrocytic) schizogony. In this chapter, we will describe the ultrastructure of each specific stage, and the morphological and functional changes of the host cells induced by malaria parasites.