[Neural plasticity after neonatal hypoxic and ischemic insult in rats].

Rats with huge porencephaly occupying the left cerebral hemisphere were used for this study. Porencephaly was caused experimentally by the ligation of the left common carotid artery and subsequent hypoxic exposure at the age of 7 days. A large band of horseradish peroxidase (HRP) positive fibers was found crossing at the pyramidal decussation to reach the contra-lateral corticospinal tract and the deeper part of the funiculus, in the cervical cord. However, a small band of HRP positive fibers was noticed to reach the ipsilateral corticospinal tract without crossing at the pyramidal decussation. This result indicates that the developing pyramidal neurons in the right hemisphere carry the plasticity even after suffering from considerable hypoxia.