Fig. 4. Ultrastructural changes in Golgi organization during RII depletion. HeLa cells were plated on a dish containing a single coverslip and incubated for 80 hours with siRNA specific for human RII. The efficiency of depletion in the culture was first evaluated by immunofluorescence detection of RII in cells attached to the coverslip. The rest of the cells were then fixed and processed for transmission electron microscopy. (A) General view of the cytoplasm of RII-depleted cells. (B-D) Different Golgi stacks are shown. They appear as whorls composed of multiple concentrically arrayed cisternae. Cisternae appear dilated and fragmented. Bars, 0.5 µm.