Figure 2.

Comparison of xanthurenic acid and human serum on in vitro ookinete development of Plasmodium vivax. Giemsa-stained thin blood smears of P. vivax sexual stage parasite cultures derived from a single patient sample were equally divided and treated with two gametogenesis protocols using either exflagellation solution (XaES) or human serum (HS). A, Cultured sexual stage parasite forms generated by using XaES to stimulate gametogenesis. Elongated forms generated using this protocol showed normal immature and mature ookinete morphology and abnormal elongated forms. Approximately 30–40% of elongated parasites derived by using this method had either immature or abnormal morphology. B, Cultured sexual stage parasite forms generated by using HS to stimulate gametogenesis. More than 90% of elongated forms generated by using this protocol showed characteristic mature ookinete morphology. Scale bars = 5 μm.