Fig. 2. Images of the actin cytoskeleton in frozen hydrated samples; the cytoskeletons were produced by 1 minute extraction in the Triton/GA mixture. (A) A filopodium protruding at the cell's edge; in the top right corner, another thick filopodium is seen. (B) A lamellipodium showing a relatively sparse network, together with filaments arranged parallel to the edge, probably corresponding to a non-protruding region (see text). (C) Sparse actin networks found in regions deeper inside the lamella; the globular structures of approximately 20x30 nm seen frequently are interpreted as ribosomes. (D) Another lamella region showing F-actin, microtubules and ribosomes. Bar, 200 nm.