Control of gamete formation (exflagellation) in malaria parasites.

The only stages of malaria parasites capable of establishing an infection in a mosquito are the gametocytes that circulate in the blood of the veterbrate host. Within minutes of ingestion by a mosquito the gametocytes transform into mature gametes in the process of "exflagellation." This process is controlled in vitro solely by the change in pH in the blood as it moves from the environment of the circulation to that of the atmosphere, the pH rise being mediated by the fall in carbon dioxide tension as the blood equilibrates with the atmosphere.