| Budget Amount *help |
¥5,300,000 (Direct Cost: ¥5,300,000)
Fiscal Year 1988: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1987: ¥4,300,000 (Direct Cost: ¥4,300,000)
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| Research Abstract |
In the comparative morphometric studies of the primary sensory neuron between young and old rats, the following conclusions were obtained. In older rats compared with younger rats, 1)the number of myelinated fibers was decreased, 2)the myelin sheath showed segmental demyelination followed by remyelination, 3)the myelin change was severe in the ventral root, 4)axonal degeneration of the myelinated fiber was more frequently found, 5)the nerve cell body in the spinal dorsal root ganglion showed higher density and shrinkage of the cytoplasm, 6)axonal swellings and spheroids were frequently found in the gracile nucleus of the medulla, but they were rare in the dorsal born of the lumbar spinal cord and in the dorsal nucleus of clarke of the first lumbar spinal cord, 7)the volume density of the nerve terminal was decreased in the gracile nucleus of the medulla, dorsal born of the lumbar spinal cord and dorsal nucleus of clarke of the first lumbar spinal cord, and the decrease was prominent in the gracile nucleus, 8)the total number of nerve cell bodies in the first sacral dorsal root ganglion was decreased, and the decrease of those with larger diameters was prominent, and 9)the unmyelinated fibers showed the tendency of the decrease in number, but the ongoing degenerative findings of unmyelinated fibers were not found. Therefore, it was concluded that the primary sensory neuron shows histopathological alterations in each component of the myelin sheath, axon, nerve terminal and nerve cell body. The large diameter sensory neuron seems to be most vulnerable in the aging process.
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