Life cycle of Plasmodium falciparum, a parasitic protozoan that causes the most severe form of malaria in humans. The bite of the female Anopheles mosquito introduces sporozoites into the human host, which mature as they travel to the liver and ultimately the bloodstream. After a blood meal from an infected person, the malarial gametocytes enter the midgut of the mosquito where they transform into male microgametes and female macrogametes. Their union leads to a zygote, which transforms into an ookinete, penetrates the intestinal wall of the mosquito, and is transformed into a circular oocyst. Inside the oocyst, the sporozoites develop from germinal cells known as sporoblasts. The sporozoites emerge from the oocysts and migrate to the salivary gland where they enter the human hosts during the blood meal of the mosquito.