Early changes in degenerating mouse sciatic nerve are associated with endothelial cells

This study determines the earliest reproducible biochemical change in nerve undergoing Wallerian degeneration by assessing the timing, magnitude, and specificity of changes in markers of cellular function in distal stumps of transected mouse sciatic nerves. Analysis of temporal changes in synthesis of DNA, RNA, protein, and in activity of ornithine decarboxylase in transected and sham-operated nerves 0-5 days postoperatively indicated that incorporation of [³H]thymidine, a marker of premitotic activity, was the earliest and only specific marker of early Wallerian degeneration. Although the 3-4 day peak in [³H]thymidine incorporation in distal stumps of transected mammalian nerves is known to reflect Schwann cell mitosis, light-microscopic autoradiographic studies of nerve stumps at the onset of the [³H]thymidine response (1 day post-transection) revealed preferential labeling of endothelial cells lining intrafascicular capillaries.