Electron microscopy of Plasmodium falciparum 1. The structure of trophozoites in erythrocytes of human volunteers

Electron microphotographs of early trophozoites of Plasmodium falciparum from human volunteers were compared with those of Plasmodium berghei in the rat. Human and rodent trophozoites exhibited certain general similarities: (1) both lacked a nucleolus, (2) pigment and smooth membrane vesicles were similar, (3) both forms exhibited double limiting membranes, (4) both lacked typical mitochondial forms, (5) both forms exhibited micropyle-type structures which are apparently specialized sites of absorption. Although multilaminated-membraned bodies (whorled-patterns) were present in both forms, P. falciparum differed in that these bodies appeared to be derived from the nuclear membranes; the origin of the body in P. berghei appeared to be more related to the external limiting membranes. The erythrocytic forms of P. berghei showed a great predilection for reticulocytes or younger red cells, but P. falciparum was found only in mature red cells.