The ookinete then becomes a static oocyst, between the basal lamina and the basement cell membrane, and bounded by a thick plasmalemma. The chief source of nutrients is the haemolymph in which the oocyst develops. Sporoblasts form, and sporozoites bud off. After the cyst ruptures, the sporozoites escape into the haemocoele and migrate to and penetrate salivary gland cells where they lie in vacuoles for up to 59 days. They are more antigenic, and bear circumsporozoite polypeptide on their plasmalemma.
Sporozoite motility is involved in their invasion of cells and escape from the salivary gland.
They posses a complex pellicle, which is responsible for motility, and contains circumsporozoite protein. The apical penetrating region contains extensions of the microneme ducts which release an agent which interacts with host cell plasma membrane during penetration. Some are destroyed by macrophages, or by antigen specific antibodies in immune individuals, but in non immune individuals, they reach the hepatocytes and initiate schizogeny or become hypnozoites depending on their delay trigger.