Is there remyelination during aging of the primate central nervous system?
Peters A; Sethares C Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA. apeters@cajal-1.bu.edu The effect of aging on myelin sheaths in the rhesus monkey was studied in the vertical bundles of nerve fibers that traverse monkey cerebral cortex in primary visual area 17 and prefrontal area 46. As shown previously, with age the internodes of many of these myelin sheaths show structural changes, the most common of which is an accumulation of electron-dense cytoplasm within some sheaths, a change which is considered to indicate that breakdown of myelin is taking place. Supporting the suggestion that myelin is breaking down with age, astrocytes in the cortices of old monkeys contain phagocytosed myelin and some of the inclusion bodies in astrocytes label with antibodies to myelin basic protein. There is also evidence that remyelination is taking place. Thus, we have found an increase in the frequency of profiles of paranodes when t
