Rhoptry organelles of apicomplexan parasites.

Rhoptries are the unifying structural feature of the intracellular, opicomplexon parasites and are implicated in having a central role in host cell invasion. Ultrastructural studies of zoites of different genera suggest that the participation of rhoptries in the invasion of the respective host cells is morphologically similar. However, biochemical analysis of their protein constituents reveals a considerable degree of diversity between different coccidion parasites. In this article Margaret Perkins asks whether there are common structural determinants of the rhoptry components of different genera and if the underlying mechanism of rhoptry function is similar in all opicomplexon parasites.