Remyelination and recovery of conduction in cat optic nerve after demyelination by pressure

Pressure has been applied to the optic nerve of cats sufficient to block conduction in the large (Y) nerve fibers. The pressure block produces a mixture of axotomy and demyelination. By means of implanted electrodes, recovery of conduction in these fibers was monitored. There is a short-term recovery starting about 2 weeks after block induction and finishing at about 4 weeks. A later recovery starts at about 67 weeks and finishes at about 10-11 weeks. The remyelination has been monitored in the electron microscope by measurement of the myelin thickness and axon diameter of the large fibers. The remyelination follows a time course similar to the late phase of conduction recovery. By reference to the work of others, we surmise that the early recovery of conduction is due to the reorganization of microtubules disorganized by the pressure. (C) 2003 Elsevier Inc. All rights reserved.