P vivax rosetting and its effect on schizont concentration. (A). The relationship between the percentage of rosetting P vivax IRBCs (in the 20-hour matured isolates) before concentration and presence or absence of a concentrated schizont band at the 45% Percoll interface. (B) A micrograph of an unstained wet preparation showing a P vivax rosette (more than one RBC attached to a central IRBC) collected from the pellet of a isolate that did not yield a band on the Percoll cushion. (C) Rosetting forms were not observed following treatment of the pellet with trypsin, and a band was subsequently obtained on the Percoll cushion. Black scale bar corresponds to 10 μm for both micrographs.