Fig. 6. Cytoskeletal rearrangement in keratocyte fragments during polarization.
(a-d) Stationary fragments that were mechanically stimulated but had not yet started to locomote. (e-h) Mechanically stimulated fragments that were initially stationary but which subsequently translocated a distance exceeding one body length. Fragments were analyzed by double fluorescence staining for actin (cyan) and myosin II (red) (a,e) and electron microscopy of platinum replicas (b-d, f-h). (b,f), Overviews and regions of (c,g), trailing and (d,h), leading edges demonstrate alignment of filaments into bundles along the trailing edge and development of crisscross actin network at the leading edge. Initial positions of perimeters of stationary fragments are indicated by dashed lines. Note that the width of criss-cross actin network at front (brackets) is greater in (h) than in (d) and that myosin II which is found throughout the fragment in (a), became concentrated at the rear after fragment travelled one body length (e). Bars, 2 mm in (a,b,e,f,), and 200 nm in (c,d,g,h).
