[Cytoskeletal changes in mouse embryonic fibroblasts exposed to colcemid. Electron microscopic research on platinum...

Cytoskeletons of colcemid-treated mouse embryo fibroblasts were studied using platinum replica technique. In the control cells, cytoskeletal components were oriented along direction of cell polarization. Structure of the control cytoskeleton changed regularly from the cell active edge to its centre forming several zones. Distribution of microtubules by colcemid led to significant changes in the organization of actin cytoskeleton. Both orientation and zonal differentiation of cytoskeleton disappeared in colcemid-treated fibroblasts. Changes in the fine structure of microfilament sheath were most prominent. Control sheath was composed of stretched tightly packed microfilaments. Colcemid treatment transformed it into fine microfilament meshwork, normally characteristic only for ruffle zone. Alterations of the fine structure of focal contacts and ruffles were also observed in treated cells. The role of microtubules in the organization of intracellular tensions and in the distribution of sites of actin polymerization is discussed.