SCHIZOGONY OF PLASMODIUM-YOELII NIGERIENS IS - ROLE OF THE LATENT MEROZOITES

Several procedures were employed to try to specify the schizogonic cyc le of Plasmodium yoelii nigeriensis. The Percoll-glucose gradient tech nique for concentrating the very young stages (rings and young trophoz oites), allowing a very precise follow up of the development of the pa rasitaemia during the first schizogonic cycles. A method for studying the prepatencies, providing an approximation of the number of merozoit es inoculated. A comparison between the numbers of merozoites present in the blood, after - 1stly simple dilutions in saline, revealing the total number of merozoites, - 2ndly dilutions in saline after a passag e of a few hours in the organism of a mouse, revealing the number of l atent merozoites. It was shown that the infection, during the first tw o cycles, varies according to the time of inoculation. In all cases th e increase of the parasitaemia occured mainly from 00:01 to 06:00. Thi s increase of parasitaemia in mice inoculated with the Percoll concent rated parasites was significantly high during the first cycle in mice inoculated at 06:00 and 09:00 and during the second cycle in those ino culated at 12:00, 15:00 and 18:00. However, differences were rapidly c ompensated and parasitaemias became comparable at the 3rd or 4th cycle when they ceased to be dependent on the time of inoculation.