Demyelinisation in the spinal cord of vitamin B12 deficient fruit bats.

1. Vitamin B12 deficiency induced in the fruit bat by a combination of dietary deprivation and exposure to nitrous oxide (N2O) is accompanied by profound neurological impairment, thus providing an experimental model for the study of vitamin B12 neuropathy. 2. Electron microscopy of the spinal cord of vitamin B12 deficient bats shows marked changes in the myelin of the posterior columns in the form of distension, separation and vacuolation of myelin lamellae similar to the changes described in the dietary induced B12 deficient monkey model. 3. No equivalent change occurred in bats exposed to N2O and supplemented with vitamin B12.