Ultrastructural view of the corpus callosum in sham and TBI animals. In sham animals, numerous intact myelinated axons with preserved cytoskeletal detail can be seen (A). In contrast, pathological changes are present in TBI animals (B, C, and D). Galectin-3/Mac-2+ microglial cell identified by the presence of DAB reaction product (arrowheads) is seen engulfing an injured axon (arrow in B). An example of an injured axon characterized by separation of the myelin sheath from the axolemma is shown (arrowheads in C). Focal swelling can also be seen within a damaged axon (arrow in D). Bar = 500 nm in A, 2 μm in B, 500 nm in C and D.