Abstract
One eyelid has been sutured in each of three sevenβday old kittens. Three months later the brains were fixed and stained by the Nissl method. In the contralateral lateral geniculate nucleus the cells of the deprived lamina A were smaller, more closely packed and paler staining than those in the normally innervated, ipsilateral lamina A. However, these changes were seen in the medial parts of the contralateral lamina A only. The lateral parts, which extend beyond the border of lamina A1 and which project to the monocular parts of the visual cortex showed no change. These results show that some geniculate cells are not affected by deprivation. The observations are consistent with the view that during normal development geniculate cell axons from adjacent laminae compete with each other for synaptic surfaces upon binocular cortical neurons: that unilateral lid suture upsets the balance of this competition and that the reduced perikaryal growth in the lateral geniculate nucleus is secondary to the unbalanced axonal development, which occurs in the binocular portions of the geniculocortical projection but which cannot occur in the monocular portions, where there is no competition.