Microtubule nucleating capacity of centrosomes in tissue sections

We used a novel adaptation of methods for microtubule polymerization in vit ro to assess the MTOC activity of centrosomes in frozen-sectioned tissues. Remarkably, centrosomes of tissue sections retain the ability to nucleate m icrotubules even after several years of storage as frozen tissue blocks. Ad aptations of these methods allow accurate counts of microtubules from indiv idual cells and the quantitative estimation the MTOC activity of the intact tissue. These methods can be utilized to characterize MTOC activity in nor mal and diseased tissues and in particular tissues at different stages of d evelopment.