[Ultrastructural characteristics of the tissue changes in the cerebral cortex during aging].

The sensorimotor, visual and temporal portions of the brain were studied in seven rats aged 30-35 months. It has been established that the process of the ageing of the cerebral cortex is characterized by the polymorphism of structural changes and heterochronism of their development in the areas studied. The sensorimotor cortical area underwent the most pronounced destructive changes whereas in the process of ageing per se the dominant feature was presented by alterations in the protein-synthetizing apparatus of the cells. The destructive changes in the neuronal tissue were paralleled by compensatory-adaptive reactions expressed in the predominant increase of the amount of a particular kind of cell organelles and the formation of various types of contacts between neurons and other elements of the cortex.