Fig. 8. Isolated axon preparations. (A-D) BDNF-stimulated axonal growth, visualized by Calcein Orange-Red fluorescence (A) is associated with migrating cells whose nuclei are labeled by DAPI (B). Axons that have extended through a Nuclepore membrane (C) are devoid of migrating cells (D). The bright foci that are visible in C represent localized thickenings of axons, not cells, as shown by the absence of DAPI labeling in D. Scale bar, 100 µm.