Complex sentence: They may be divided according to the type of axon affected: large-fiber, small-fiber, or both, the most distal portions of axons are usually the first to degenerate, and axonal atrophy advances slowly toward the nerve's cell body.
Split into simpler sentences: They may be divided according to the type of axon affected: large-fiber, small-fiber, or both. The most distal portions of axons are usually the first to degenerate, and axonal atrophy advances slowly toward the nerve's cell body.