Figure 2.

Neurite growth on ex vivo crushed spinal cord A, Fluorescein-labelled neurites extending on a horizontal section through crushed spinal cord white matter. Long parallel neurites extended on the uncrushed segments of white matter but did not extend onto crushed white matter. B, An adjacent section showing GFAP immunoreactivity within the crushed white matter (wm). Edges of the crush are indicated by white arrowheads. C, Neurites extending on crushed and uncrushed spinal cord white matter. Neurites extended in parallel on uncrushed segments of spinal cord white matter but terminated at edges of the crushed region of tissue (white arrow). Neurites extending from neurons attached directly on the crushed region often extended in non-parallel orientations and appeared to use each other as a substrate (white arrowhead). D, Phase-contrast photomicrograph of the same field shown in panel C. The crushed white matter is evident from its increased optical density. The edges of the crushed segment of white matter (wm) are indicated by black arrowheads. E, Neurites extending on crushed and uncrushed segments of spinal cord white matter. Several of these neurites appeared to use each other as a substrate as they approached the crushed tissue and turned in non-parallel orientations (white arrow). A neuron attached directly to crushed white matter did not extend a neurite (white arrowhead). Neurites extending on gray matter (white asterisk) appeared to be unaffected by the crush. F, Phase-contrast photomicrograph of the same field shown in panel E. G, Neurites extending on uncrushed white matter did not extend onto crushed white matter (white arrow). Neurites extending on gray matter (white asterisk) were not inhibited by crushed gray matter. H, Phase-contrast photomicrograph of the same field shown in panel G. gm, gray matter. Scale bars: A, 250 μm; C, E, 100 μm; G, 250 μm.