Figure 2.

Microtubule polarity analyses performed on processes extended by neuroblastoma cells. In the axon-like processes extended by normal interphase cells, the hooked appendages on the microtubules are predominantly clockwise (A). In the dendritelike processes extended by these cells, roughly equal proportions of the hooks are clockwise and counterclockwise (B). In the dendrite-like processes extended in the presence of retinoic acid, roughly equal proportions of the hooks are clockwise and counterclockwise (C). In the axon-like processes extended in the presence of db cAMP, the hooks are predominantly clockwise (D). Bar, 0.08 μm.