HEXACHLOROPHENE‐INDUCED LESIONS IN THE DEVELOPING PERIPHERAL NERVOUS SYSTEM OF MICE

Hexachlorophene‐induced lesions in the developing peripheral nervous system of mice Hexachlorophene (HCP) locally applied to the sciatic nerve of mice less than 2 weeks old caused a marked sponginess of the myelin. Ultrastructurally, this was due to a splitting of the minor dense lines of the myelin lamellae with the formation of vacuoles. The changes were reversed after discontinuing the treatment. Unexpectedly, this sponginess in the peripheral nerves was much less and failed almost completely to occur when the HCP application was continued after the second week of life. HCP treatment given to mice older than two weeks caused no sponginess of peripheral nerves, but status spongiosus instead developed in the white matter of the central nervous system. The only change in the peripheral nervous system (PNS) in the older mice was a Wallerian type of degeneration of nerve fibres at and distal to the site of HCP injection. It is therefore concluded that the response of the myelin of mouse PNS to HCP is age dependent and differs from the responses of CNS myelin.