SummaryThere is no absolutely clear point at which early trophozoites of P.vivax become late trophozoites as it is simply a process of continuous development. However, the transition to an amoeboid parasite form where the original ring structure can no longer be seen will certainly place the parasites at this stage.
Developing late trophozoite The ring form is lost, the parasite is very irregular
Late trophozoite Note the solid parasite and the red cell begins to show distortion.
Late trophozoite Similar to the previous example, the ring structure is entirely lost
Classical amoeboid form note also the very enlarged distorted red cell
