Organization of Actin Meshworks in Cultured Cells: The Leading Edge

Since the arly studies of Buckley and Porter (1967), Spooner el al. (1971), and others (see Goldman et al. 1976), it has been generally recognized that F-actin in cultured cells occurs in at least wo distinguishable states of structural organization: in linear fibrillar bun-dles, normally recognizable in the light microscope and commonly referred to as "stress fibers, " and in mesh-works or networks, confined to the motile lamella zones and ruffling membranes and thought o be gen-erally present beneath the plasmalemma in a subcorti-cal layer (Spooner et al. 1971; Goldman et al. 1976). In many subsequent studies the existence and general organization of the more obvious stress-fiber bundles, as well as the indentification of microfilaments within them as F-actin, have been exhaustively documented