Hemispherectomy in the newborn hamster: effect on cell death in the extraocular motor nuclei.

In order to test the effect of removing the corticonuclear pathway on the development of the extraocular motor nuclei, a hemispherectomy was performed in newborn hamsters. After a survival period of 20 days, the number of neurons in the extraocular motor nuclei was compared to that of intact animals. The number of neurons in the stated nuclei showed a significant reduction in the experimental animals in comparison to controls. The decrease in the number of neurons affected all types of cells. Both sides of the brain showed the reduction in the number of neurons, although more intensely in the contralateral side. The results stress the importance of normal cortical input in regulating regressive phenomena in subcortical motor nuclei.