Abstract
By double indirect immunofluorescence, using guinea pig and rabbit antibodies to tubulin and to desmin, we have simultaneously labeled microtubules and intermediate filaments in cultured chicken embryo gizzard cells. At the resolution of the light microscope there was extensive but not complete superposition of the labeling patterns for the two filamentous structures within cells in interphase and an essentially complete dissociation of the two labeling patterns in cells in mitosis. These results indicate that there is an extensive association of microtubules and intermediate filaments in these interphase muscle cells and suggest that this association is regulated metabolically.