The flagellum in malarial parasites.

The malarial parasites assemble flagella exclusively during the formation of the male gamete in the midgut of the female mosquito vector. The observation of gamete formation ex vivo reported by Laveran (Laveran MA: De la nature parasitaire des accidents de l'impaludisme. Comptes Rendues De La Societe de Biologie. Paris 1881, 93:627-630) was seminal to the discovery of the parasite itself. Following ingestion of malaria-infected blood by the mosquito, microgamete formation from the terminally arrested gametocytes is exceptionally rapid, completing three mitotic divisions in just a few minutes, and is precisely regulated. This review attempts to draw together the diverse original observations with subsequent electron microscopic studies, and recent work on the signalling pathways regulating sexual development, together with transcriptomic and proteomic studies that are paving the way to new understandings of the molecular mechanisms involved and the potential they offer for effective interventions to block the transmission of the parasites in natural communities.