Differentiation of gametocytes in microcultures of human blood infected with Plasmodium falciparum.

Gametocytes differentiated from ring-stage parasites in microcultures of human blood infected with Plasmodium falciparum. Immature gametocytes could be distinguished morphologically from late asexual trophozoites after approximately 40 h of culture. Differentiation into crescentic forms took several days and the incorporation of [3H]-isoleucine by developing gametocytes was demonstrated. About 1% of red cells contained gametocytes at the maxiumum densities attained. Differentiation of gametocytes occurred either directly from rings placed in culture or from the progeny of subsequent cycles of schizogony and invasiton in vitro. The latter occurrence was confirmed by the development of gametocytes in marker fetal red cells added to cultures, although fetal red cells provide a less favorable environment than those with HbA for growth of the parasites.