Figure 2.

Effects of taxol on microtubule organization in axons and dendrites. In control neurons, microtubules are nearly uniformly plus-end-distal in the axon. In the dendrite, microtubules have a mixed orientation (A). Each microtubule consists of a stable domain toward the minus end of the microtubule, with most microtubules also consisting of a dynamic (labile) domain toward the plus end of the microtubule. Dendritic microtubules are less stable than axonal microtubules, as indicated by shorter stable domains on dendritic microtubules in the illustration. In neurons treated with taxol (B), the density of microtubules increases, the normal domain structure of individual microtubules is lost because the microtubules are stabilized all along their lengths, and flaws arise in the normal polarity patterns of the microtubules. Such abnormalities can lead to degeneration of axons and dendrites.