Observations on the vimentin-10-NM filaments during mitosis in BHK21 cells.

Mitotic BHK21 cells were examined by immunofluorescence optical sectioning after staining with anti-vimentin. Throughout all stages of mitosis, intact 10-nm filaments were observed to form a cage around the mitotic spindle. These observations were confirmed by serial section electron microscopy which demonstrated assembled 10-nm filaments in the cytoplasm surrounding the spindle. Therefore, in contrast to previous reports, mitotic BHK21 cells show a similar cage-like 10-nm filament arrangement, as found in a variety of other cell types.