Scanning electron micrograph of two Plasmodium ookinetes (purple). This motile life form is a fertilized zygote that burrows into the wall of the mosquito midgut in order to develop into an oocyst. This represents one stage in the malaria parasite life cycle. Cellular debris (yellow) from the growth medium is also visible. Plasmodium is a parasitic protozoa that causes malaria. Each parasite measures 12 micrometres. Supplied by Leandro Lemgruber, University of Glasgow, courtesy of Wellcome Images.