Gametocytes present emerge from their red cell hosts, and become haploid gametes. A male and a female gamete fertilise to become a diploid zygote, called an ookinete. This is the only diploid stage of the parasite's lifecycle. The ookinete moves through the bloodmeal, crossing the peritrophic matrix surrounding the blood bolus, and penetrates the mosquito midgut epithelium. It then encysts on the outer wall of the midgut, and develops over the next 7 to 14 days as an oocyst.
Sporozoites develop within the oocyst and migrate in haemolymph to invade the salivary glands.
When the mosquito takes another bloodmeal, sporozoites pass with the mosquito saliva into the next host. Parasite genetics All of the parasite stages within the human host are haploid. Meiosis occurs following the fusion of the male and female gametes in the mosquito midgut. The resulting ookinete is the only true diploid in the parasite's lifecycle. During meiosis there is the opportunity for recombination .