MICROTUBULE DYNAMICS IN LIVING CELLS

Most people think of a skeleton as a solid and static framework upon w hich complex structures are elaborated. From what we have learned in t he past decade about the cytoskeleton, it seems certain that the 'skel eton' part of the term is a bit misleading. It is clear now that the p olymers that constitute the cytoskeleton, actin filaments, microtubule s, and intermediate filaments, are all in fact ever-changing dynamic i nfrastructures of cells. Recently, advances have been made in the stud y of the cellular dynamics of one of the prominent components of the c ytoskeleton, the microtubules. Observations in the past year have reve aled some fundamental in vivo behaviors of these polymers, during inte rphase, during mitosis, and during the elaboration of postmitotic axon al microtubule arrays. These observations are important for the unders tanding of cytoplasmic organization in many types of cells.