Ultrastructure of human cerebral cortical synapses: age-specific aspects

The paper deals with electron microscopic studies of the cerebral cortex in human beings aged 70-80 years. The synapses show a decrease in the number of synaptic vesicles, their impaired distribution in the presynaptic process. There are changes in the mechanisms of interaction of synaptic vesicles and a presynaptic membrane. In the latter, the vesicles loose their discreteness, some of them are replaced by a fine-granular material. The joining of the vesicles and membrane is impaired. A part of active synaptic areas is transformed to desmose-like contacts. The findings are indicative of synaptic dysfunction.