Kinetochore microtubules, analyzed by correlated light and immunoelectron microscopy

The movement of chromosomes in mitosis requires spindle microtubules, as well as a set of specific motor proteins located at the kinetochores of the chromosomes. The exact mechanisms of chromosome movement have remained ambiguous for many years. Cumulating evidence indicates that chromosome movement in early mitosis occurs by lateral sliding of kinetochores along the surface of microtubules. We provide here the protocol for an immunological staining method of microtubules that allows electron microscopic analysis of spindle microtubules over a long distance and that has helped clarifying this biological question. The technique involves the use of ultra-small immunogold, enhanced by silver.