Fig. 6.

Schematic representation of tomaculi formation in MAG-deficient paranodal regions. A–C, Relationship between axonal caliber and myelin sheath in transverse section of normal myelinated fiber (A). In MAG-deficient nerves, paranodal axonal calibers shrink (B) and result in myelin sheath collapse and tomaculi formation (C). D, In MAG+/+ paranodal regions, increased neurofilament spacings correlate with large axonal caliber. In MAG−/− paranodal regions surrounded by tomaculi, neurofilament spacings and axonal calibers are similar to those in nodal regions.