[Structural changes in the cytoskeletal actin in cultured muscle cells when the cultures are stimulated by polystyrene latex].

As we reported elsewhere, the addition of polysterol latex (180 nm) to chick muscle culture accelerated several myogenesis stages, such as proliferation and fusion. In the present work we tried to determine the role of cytoskeletal actin in the mechanism of acceleration. The localization of cytoskeletal actin was studied in normal and latex induced cultures with the help of rodamine--phalloidin. The obtained data have shown that latex beads added to the cultural medium brought about acceleration of cell spreading (the number of spread cell was approximately five times more in comparison with the norm) and enhanced the development of actin network (90% of the cell area was filled with stress-fibrils in 20 h, instead of within 1-3 in the norm). It is proposed that muscle cells interact primarily with latex beads in the cultural medium before seeding on the glass. From this point of view latex beads can be considered as a primary substratum. The cell contact with the primary substratum initiates the actin network reorganization that leads to activation of cell spreading with a subsequent acceleration of myogenesis process: adhesion, proliferation and fusion.