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The corticospinal tract in the rat after neonatal ablation of the unilateral cerebral
cortex was studied morphologically and histochemically using the retrograde and antegrade
horseradish peroxidase (HRP) tracing methods. The normal corticospinal tract in the
lumbar cord was composed of a number of small and some large axons. In the atrophic
corticospinal tract related to the ablated cerebral cortex, the small axons were decreased
in number two weeks after the operation. However, new myelinated small axons appeared
around day 28 and their diameters increased gradually from after day 56 to day 84.
The original large axon in the atrophic corticospinal tract was much more increased
in size than that in the corticospinal tract of the non-operated-on control. When
HRP was injected into the left cervical cord of the adult rat whose right cerebral
cortex had been ablated during the neonatal period, a considerable number of HRP-labeled
neurons was seen in the healthy left cerebral cortex. When the corticospinal tract
was traced antegradely by injecting HRP into the healthy left cerebral cortex, an
aberrant corticospinal tract reaching into the ipsilateral dorsal funiculus was observed.
These results give a morphological basis for the well known fact that children who
have had brain damage during the neonatal period and early infancy have the capacity
for recovery of motor function.
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Article info
Publication history
Accepted:
October 11,
1989
Received:
June 26,
1989
Identification
Copyright
© 1990 Published by Elsevier Inc.
