The pattern of recovery of axons in the nervous system of rats following 2,5-hexanediol intoxication: a question of rheology?

Rats have been dosed with 2,5-hexanediol for 48 days and then allowed to recover. The changes in the accumulations of neurofilamentous masses in various pathways in CNS and PNS have been followed by light microscopy over the subsequent 9 weeks. It was found that many CNS pathways allow the argyrophilic masses to pass to their terminals from whence they subsequently disappear, usually over 5-6 weeks. Little or no axonal degeneration is seen where this happens. The same occurs in many peripheral nerves, particularly cranial nerves. However, in many tracts in the spinal cord and in many axons in the longer peripheral nerves, filamentous masses remain and becomes associated with axon degeneration, and, in tracts, gliosis. The importance of paranodal constrictions at nodes of Ranvier which tend to be greater in larger diameter axons is emphasized as a likely mechanism for the axon degeneration which largely took place during the recovery period.