Fig. 4. In contrast to osmotropes, `crowders' promote chromatin compaction, if they gain access to the cell. The chromatin distribution (ToPro3) in MCF7 nuclei was challenged by incubation with NaCl and/or dextran for 15 minutes in combination with digitonin permeabilization of the cells. The incubation sequence for each example is indicated. Digitonin treatment abolished chromatin compaction by NaCl (top row). In contrast to cells with intact membranes (see Fig. 3B), dextran induced chromatin compaction when cells were permeabilized (bottom row). Dextran still asserted this effect in cells where previous chromatin compaction upon hypertonic incubation with NaCl had been abolished because of digitonin permeabilization (right). Bar, 10 µm.