Age-related changes in the neuropil in the rat inferior olive nucleus: quantitative electron microscopic study.

Age-related ultrastructural changes in the neuropil in the rat inferior olive nucleus were examined at 3, 6, 12, 18, 24 and 30 months old. The profiles of axon terminals, dendrites and astroglial processes from random samplings within the neuropil were traced. Subsequently, the percentages of these profiled areas in relation to the area of neuropil (relative volume fraction) were examined using the image analyzer system. The relative volume fractions of both axon terminals and dendrites in relation to the neuropil were found to have decreased in the aged rats, while the relative volume fraction of astroglial processes had progressively increased with aging.