Synaptic mitochondria and ageing: computer-assisted morphometry in rat cerebellar glomeruli.
The ultrastructural features of synaptic mitochondria have been investigated by means of computer-assisted morphometry in the cerebellar glomeruli of young, adult and old rats. The volume fraction occupied by mitochondria (volume density: Vv), the number of organelles/ microm(3) (numerical density: Nv), the average volume (V) and the average length (Sk) of the mitochondria were the parameters measured in electron microscopic photos taken at an enlargement of x 8000. Vv showed a lifespan constancy. Nv was increased in the adult group vs. the young, but it was decreased in old animals as compared with the other 2 groups of age studied. V and Sk showed the same age-dependent changes: a significant decrease in the adults and a significant increase in the old rats vs. the other groups analysed, respectively. We interpret these findings to represent age-dependent morphofunctional adaptations occurring at synaptic mitochondria as a response to actual energy demands from the synaptic connectivity they subserve. Although impaired, the dynamic morphology of synaptic mitochondria appears to be capable of consistent compensative ultrastructural rearrangements in the central nervous system of old individuals.
Bertoni-Freddari
C
C
Centre for Surgical Research, INRCA Research Department, Via Birarelli 8, 60121 Ancona, Italy.
Fattoretti
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P
Meier-Ruge
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W