Figure 10.

Microtubule stabilization changes the position of axon outgrowth. A, The axon (black arrowheads) grows proximal to the centrosomal pole (inset at right, red arrowhead) in control cells. B, Microtubule stabilization with taxol (10 nm) changes the axon outgrowth position in some multipolar cells. Aberrant initial trajectory of the axon that is proximal to the centrosomal pole (inset at right, red arrowhead). Distal parts of the axon project properly. C, D, Quantification of the centrosome (dots) and axon outgrowth position (lines) in control cells (C) and after taxol treatment (D). In each quadrant, dots and lines with unique colors represent a single cell. E, Model of microtubule dynamics in multipolar and bipolar neurons. Microtubule dynamics regulate the rotation of the centrosome (red dots) toward the VZ in multipolar cells; this centrosomal positioning underlies axon formation. Subsequently, stable microtubules form a microtubule aster in bipolar migrating neurons (red lines), to promote nuclear translocation and axon elongation. Scale bars: A, B, 10 μm.