Detection of nestin in the cell nucleus. Labeled nestin was distinctly detectable also in the cell nucleus as individual particles and small clusters of signal (A); several larger nestin aggregates (B–C) were also observed. Arrows indicate very short fibers in these aggregates (B–C). A special arrangement into short spiral-like fibers in cell nucleus (D–E) was found repeatedly in different cells. Nestin was detected using immunogold labeling; bars, 1 μm (A), 0.1 μm (B–E). Negative control stained with secondary antibody only: nucleus and nucleolus (Nu); bar, 0.5 μm (F).