| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1988: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1987: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Research Abstract |
The behavior of the oligodendrocytes during myelin formation with special reference to the development of the nerve tracts was investigated by using neurological mutants, mld (myelin deficient mouse) and shiverer, which are the autosomal recessive mutation. The results are as follows:
1. By the Golgi silver stain the immature oligodendrocytes of both normal and mld possessed predominantly numerous cytoplasmic processes, several of which were associated closely with axons in the nerve tract (the pyramidal tract in this study). The inherited defect that myelin basic protein is absent in the central myelin was not related with the initial behavior that oligodendrocytic processes apply to the axons to enclose them.
2. The myelin lamellae of mld are prinicipally consisted of tri-lamellar units without the major dense lines quitely resembling those of the shiverer. However, as for mld myelin lamellae, the major dense lines occurred sporadically and with different amount among different myelin
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sheaths. This means that the structure and chemical composition of the internodal segments of myelin lamellas are determined by the oligodendrocytes concerened.
4. At 4-5 day after birth when the pyramidal tract could reach the target neurons in the spinal cord, as detected by diI (a supersensitive fluorescent dye ) injection into the motor cortex, the oligodendrocytes of the mld in the pyramidal tract predominant increased in number, resulting in the oligodedrocytic hyperplasia in the adult pyramidal tract, and in addition, raised the disintegration of the Golgi complex and rough-surfaced endoplasmic reticulum. This phenomenon reveals the oligodendrocytic reaction to the axons might be induced by establishment of the connection of axons with the target neurons. 5. From the findings of the myelin lamellae and oligodendrocytes of the frist hybrid mice produced by intercrossing homozygotes of shiverer and mld, these two mutations were allelic, and the morphology of the myelin lamellae were closely similar to those of the shiverer, whereas some aspects revealed the properties of those of mld. Less
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