to elucidate the mophological changes of rat sciatic nerve in relation to ageing, electron microscopic studies were carried out. The author measured the diameter of nerve fibers and axons and the thickness of myelin sheaths in 2 week old, 1 month
old, 4
month old, 6 month old, 12 month old and 24 month old rats, respectively.
@ES The results were summarized as follows;
@EN 1. The diameters of nerve fibers were 6.92μm in 4 month old, 8.39μm in 1 month old, 7.29μm in 2 month old, 7.33μm in 4 month old, 8.39μm in 6 month old 9.74μm in 12 month old and 11.56μm in 24 month old rat, respectively.
2. The diameters of axons increased with age, and the mean valves of the axon diameters were 5.00μm in 2 week old, 5.13μm in 1 month old, 5.23μm in 2 month old, 5.50μm in 4 month old, 5.41μm in 6 month old, 6.63μm in 12 month old and
7.22μm
in
24 month old rats, respectively.
3. The thickness of myelin sheaths in the myelinated nerve fibers were 2.37μm in 2 week old, 2.09μm in 1 month old, 2.08μm in month old, 2.13μm in 4 month old, 2.92μm in 6 month old, 3.00μm in 12 month and 3.93μm 24 month old rats,
respectively.
4. The g ratio(diameter of mylein sheath/diameter of nerve fiber) of myelinated nerve fiber showed 0.72 in 2 week old 0.70 in 1 month old, 0.70 in 2 month old, 0.71 in 4 month old, 0.64 in 6 month old, 0.68 in 12 month old and 0.67 in 24 month
old
rats, respectively.
5. The initial degenerative changes of sciatic nerve were observed at least in 24 month old rat, and these things showed vacuoles in cytoplasm of Schwann cells and the degeneration of myelin sheath.
These results indicate an increase of sciatic nerve fiber and a decrease of g ratio in rat sciatic nerve in relation to age, and also its initial morphological changes a least in 24 months old rats.
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