A fine structural study of degenerative changes in the dorsal column nuclei of aging mice. Lack of protection by vitamin E.

The dorsal column nuclei of young, old, and vitamin E-supplemented old mice were examined by light and electron microscopy. Evidence of neuroaxonal dystrophy (NAD) was found in young (3-mo.-old) mice and increased with age. Vitamin E, added to the diet in the amount of 0.3%, did not protect the nuclei from age-associated degeneration. The NAD was characterized by enlarged profiles containing patches of smooth reticular networks and groups of vesicles. Various stages of mitochondrial alteration, producing multivesicular bodies as intermediate stages, were found, and other unusual forms of dense bodies were also observed. Axons, synaptic terminals, and possibly glial cells were affected, and, by 23 mo. of age, a large number of nerve fibers in nucleus gracilis were dystrophic, while nucleus cuneatus was affected to a lesser extent.