Cytoskeleton of living, unstained cells imaged by scanning force microscopy.

Subsurface cytoskeletal structure can be visualized in either fixed or living mammalian cells in aqueous medium with approximately 50 nm resolution using the Scanning Force Microscope (SFM). In living cells, changes in cell topography, or subsurface cytoskeleton caused by the introduction of drugs (colchicine) or cross-linking of surface receptors (by antibodies against IgE bound to the IgE receptor) can be followed in time. Contrast in SFM images of cell surfaces result from both topographic features of the cell and from variations in cell surface "stiffness". The SFM is therefore capable of measuring local compliance and stress in living cells, and so should make it possible to map the cytoskeletal forces used to generate cell motions and changes in cell shape.