Incubation of IRBCs with AlF reveals vesicle chains. (A-B) Ultrastructural characterization of glutaraldehyde-fixed trophozoite stage IRBCs revealed vesicles with an electron-dense limiting membrane arranged in chains in the RBC cytosol (black arrowhead) or (C) closely apposed to the erythrocyte plasma membrane. A typical Maurer cleft is observed (A; white arrowhead). (D) Immunoelectron microscopy confirmed the long, slender unit membranes in the RBC cytosol are Maurer clefts. MC indicates Maurer cleft; P, parasite; PVM, parasitophorous vacuolar membrane; PPM, parasite plasma membrane, RBCM, red blood cell membrane; and V, vesicles. Scale bar = 70 nm.