The distribution of actin in non-muscle cells : The use of actin antibody in the localization of actin within the microfilament bundles of mouse 3T3 cells

Living mouse 3T3 cells display a complex array of fibrous structures which are visible with phase contrast, Nomarski and polarized light optics. When cells are fixed and stained for indirect immunofluorescence with actin antibody, the same fibers show intense fluorescence indicating that they contain actin. Electron microscopy reveals that these fibrous structures consist of submembranous bundles of microfilaments located primarily on the attached side of the cells. The results are discussed in terms of the intracellular localization of a possible submembranous contractile system involved in motile activities such as cell locomotion.