Ultrastructure of the asexual blood stages of Plasmodium falciparum.

Plasmodium falciparum is the most deadly of the human malaria parasites. The particular virulence of this species derives from its ability to subvert the physiology of its host during the blood stages of its development. The parasite grows and divides within erythrocytes, feeding on the hemoglobin, and remodeling its host cells so they adhere to blood vessel walls. The advent of molecular transfection technology, coupled with optical microscopy of fluorescent protein reporters, has greatly improved our understanding of the ways in which the malaria parasite alters its host cell. However, a full interpretation of the information from these studies requires similar advances in our knowledge of the ultrastructure of the parasite. Here we give an overview of different electron microscopy techniques that have revealed the fine structure of the parasite at different stages of development. We present data on some of the unusual organelles of P. falciparum, in particular, the membrane structures that are elaborated in the erythrocyte cytoplasm and are thought to play an important role in trafficking of virulence proteins. We present and discuss some of the exciting whole cell imaging techniques that represent a new frontier in the studies of parasite ultrastructure.