Figure 3

( Above ) Median nerve. (Center) Radial nerve. (Below) Ulnar nerve with toluidine blue staining at 400× magnification. (First column) Smaller, disorganized myelinated fibers, with qualitatively increased amounts of myelin infolding, crenation, and debris are seen at the distal end of each proximal nerve stump. Regenerative clusters with axon sprouting are more prevalent at the distal ends, as is the amount of connective tissue stroma. (Second, third, and fourth columns) The myelinated fibers become progressively more organized and larger at 5, 10, and 15 mm proximally, although myelin debris and crenation are still noted. (Fifth column) The control nerves demonstrate organized, circular, and larger fibers with no noticeable myelin debris.