Cellular changes in the lateral geniculate nucleus of the cat and monkey after section of the optic tract.

Cellular changes in the lateral geniculate nucleus following section of the optic tract have been studied in adult cats and monkeys. The cats were allowed to survive for periods varying from 20 to 363 days after operation, and the monkeys from 14 to 90 days. No cellular changes were seen in the lateral geniculate nucleus of the cat at survivals up to 120 days. After 200 days, however, there was shrinkage of the cells in all laminae and measurements showed this to be between 20 and 30%. In the monkey shrinkage of cells was found, and was up to 30% after 28 days and 40% after 90 days. The delayed onset of the cellular shrinkage in adult cats resulting from section of the optic tract, as compared with that occurring after eye enucleation (63 days), suggests that even in adult cats there is some degree of 'competition' present between cells of the laminae related respectively to the ipsilateral and contralateral eye.