Observations of NC24 cells (the insect vector cells of RDV) cultivated on EM grids. (a) A light microscopy image of RDV-infected NC24 cells grown on an EM grid. Bar: 100 µm. (b) Low-magnification cryo-EM image of the NC24 cell cultured on the EM grid. The cell is outlined with a white dashed line. The cell periphery was thin enough to allow observation of the cellular structures, while the central part of the cell was too thick for imaging and appeared as a dark region. Bar: 4 µm. (c) High-magnification cryo-EM image of the NC24 cells cultivated on the EM grid. The fine membrane structures of mitochondria (M) were clearly visible. (Inset) Enlarged view of the boxed region. Bar: 400 nm.