In erythrocytes or leukocytes, merozoites develop into gametocytes. In P. falciparum, gametocytes are produced from asexual stages. Other merozoites develop into immature gametocytes, which are the precursors of male and female gametes. Some merozoites differentiate into sexual forms, male and female gametocytes. The gametocytes like the schizonts are large. The gametocytes like the schizonts are small. In the mosquito, the gametocytes move along with the blood meal to the mosquito's midgut. A mosquito ingests gametocytes when it takes a blood meal from an infected primate host. In the mosquito, the gametocytes undergo sexual reproduction to a zygote, which turns into ookinete. These gametocytes remain in the blood to be ingested by mosquitoes. Male gametocytes are called "spermatocytes", and female gametocytes are called "oocytes". The large gametocytes tend to grossly distort the infected cells and make cell identification difficult. The development of gametogonia to primary gametocytes is called gametocytogenesis. Only gametocytes are found in the blood. Male gametocytes are called Spermatocyte and female gametocytes are called Oocytes.