A scaffold to determine cell shape. Forms spindle fibers for separating chromosomes during mitosis. Arranged in geometric patterns inside flagella and cilia, used for locomotion. Very different from bacterial flagella. EM Studies John Heuser has developed techniques for visualizing cellular fibers that involve the use of detergents to remove cell membranes and soluble proteins leaving the cytoskeleton.
Cells are then rapidly frozen and prepared for the electron microscope.
Heuser, J. and Kirschner, M., J. Cell. Figure 3 from his paper shows the detergent extracted cells with diverse filaments through out the cell cytoplasm. Microtubules can be removed from the cell preparation if glycerol is left out of the buffer. Figure 7 from his paper shows the thick myosin bound actin filaments with crosslinking intermediate filaments. Microtubules- grow out of the centrosome to the cell pheriphery.