Inoue can be considered the father of the field of cytoskeleton dynamics. In the 1940s and 50s he built the first microscope capable of imaging dynamic processes in live cells, using polarized light, and proved for the first time that the mitotic spindle is composed of aligned protein fibers. We now know these fibers are microtubules. By perturbing cells with agents that cause microtubules to depolymerize (e.g. colchicine or high pressure) or polymerize excessively (e.g. D2O), Inoue demonstrated that spindle fibers are in a state of rapid dynamic equilibrium with a pool of soluble subunits in the cytoplasm. He went on to show that artificial polymerization and depolymerization of spindle fibers can generate forces within the cell, and proposed that chromosomes are normally moved by such forces during mitosis. These ideas were summarized in a seminal review in 1967. He also was the first to develop video microscopy, and wrote a major textbook on the subject. Consistent with Inoue's pioneering ideas, it is now widely believed that chromosome movement during mitosis is powered by microtubule depolymerization. We also know that force generation by polymerization and depolymerization of cytoskeletal protein fibers is perhaps the most ancient of motile mechanisms within cells, whose use extends back to bacteria.
^Inoue S (1953). "Polarization optical studies of the mitotic spindle 1. The demonstration of spindle fibers in living cells". Chromosoma5: 487–500. doi:10.1007/bf01271498.
^Inoue S, Sato H (1967). "Cell motility by labile association of molecules. The nature of mitotic spindle fibers and their role in chromosome movement". Journal of General Physiology50: 259–292. doi:10.1085/jgp.50.6.259.
^Inoue S, Spring K (1997). Video Microscopy: the Fundamentals. Plenum Press, New York.