In vitro maturation of the exoerythrocytic stage of Plasmodium knowlesi observed under phase contrast microscopy.

Exoerythrocytic stages of Plasmodium knowlesi were obtained in primary culture of rhesus monkey hepatocytes. The development of a single parasite was followed with phase contrast microscopy until release of merozoites in slightly less than 5 days. This direct observation may offer opportunities to determine visually factors that may influence specific steps of schizont development.