| Co-Investigator(Kenkyū-buntansha) |
YAMAMOTO Hisashi Shiga University of Medical Science, Pediatrics Ex-Junior lecturer, 医学部, 助手 (20174807)
OHNO Masaki Shiga University of Medical Science, Pediatrics Junior lecturer, 医学部, 助手 (50194254)
KAWASAKI Hisaki Shiga University of Medical Science, Pediatrics Ex-Junior lecturer (00177669)
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| Research Abstract |
The right cerebral cortex of l-, 7-, 14-, 28- and 56-day-old rats was ablated by electrical coaguration. After 2 to 3 months of operation, the cerebrum, pons and spinal cord of these rats were examined histologically and histochemically using the retrograde and antegrade horse radish peroxidase(HRP) method. The left corticospinal tract at the posterior funiculus in the spinal cord showed severe atrophy. However, left corticospinal tract in the spinal cord of 2-months-old rat, which had had neonatal operation, showed considerable increase in small myelinated fibres.
The retrograde HRP examination for normal adult rats in which HRP had been injected into left cervical cord, demonstrated a number of HRP positive neurons to be localized at the 5th layer of the right cerebral cortex. Whereas, in the neonatally operated rats, which had HRP injection into left cervical cord, a few HRP positive neurons were found at the 5th layer of ipsilateral left cerebral cortex. However, HRP positive neurons were not found in the left cerebral cortex of the rat which had had an electrical ablation of the right cerebral cortex after 4 weeks of age.
When HRP was injected into the left sensori-motor cortex of normal adult rats and HRP positive fibers were retrogradly traced, all of the HRP positive fibers crossed over the pyramidal decussation to reach the right posterior funiculus where the corticospinal tract fibers concentrated. At the pyramidal decussation of 2- and 3-months-old rats, which had had right cortical ablation on postnatal days 1, 7, or 14 , a few HRP positive fibers were noticed extending to the right posterior funiculus without crossing over. These ipsilateral corticospinal fibers were more in number in the neonatally operated rat. Very few HRP positive ipsilateral fibers were found in the rats operated on 28 days of age, but were not in adultly operated rats.
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