Intracellular Phagotrophy in <i>Babesia rodhaini</i> as Revealed by Electron Microscopy*

Abstract

SYNOPSIS. An electron microscope study of thin sections of Babesia rodhaini parasitizing mouse erythrocytes showed that this intracellular parasite feeds on its host cell in the same way as do malarial parasites. Large portions of erythrocyte cytoplasm are engulfed by invaginations of the plasma membrane leading to the formation of food vacuoles. The digestion of hemoglobin seems to be complete in Babesia since no pigment (hemozoin) could be detected either in the food vacuoles or in the cytoplasm. The fine structure of Babesia rodhaini is very similar to that of Plasmodium berghei. In both, typical mitochondria are lacking. Instead a structure was found composed of concentric membranes which it is assumed might perform mitochondrial functions. As in Plasmodium berghei a double‐membraned vacuole with a matrix of low density is present in almost all sections. The endoplasmic reticulum is represented by small vesicles; the ground‐substance is filled with Palade's small particles. The nucleus is large and surrounded by two membranes. Babesia reproduces by budding and binary fission. Reproduction is not easy to identify since the parasite forms large pseudopods resembling stages in division.