[Role of the cytoskeleton in the spreading process of epithelial cells]

The role of microtubules and actin filaments in spreading of the IAR-2 cells isolated from the rat liver was studied. At the glass surface in the standard medium the cells rapidly assumed a discoidal form soon after inoculation. In the colcemid-containing medium the spreading is disturbed and delayed. In the cytochalasin D-containing medium the cells form two or more long processes. The effects of these drugs are reversible. It is supposed that microtubules are essential for sending cytoplasmic processes and stabilizing those processes and lamellae which have no numerous and stable contacts with the substrate, e.g., the processes which form at the early stages of spreading or the elongated processes of polarized cells. Bundles of actin microfilaments are essential, in particular, to ensure the discoidal form of epithelial cells. Microtubules appear to prevent the actin cytoskeleton contraction.