On the distribution of retinal afferents to the primate lateral geniculate nucleus

A quantitative study has been carried out on the number of synaptic ring images, visible after neurofibrillar silver impregnation, in laminae 5 and 6 of the primate lateral geniculate nucleus in normal animals and after enucleation of the contralateral eye. In a statistical experiment the number of rings was found to be significantly increased between 6 and 11 d after unilateral enucleation in both lamina 6 and lamina 5 of the contralateral geniculate nucleus. Analysis of the time course of ring proliferation suggests the presence of 2 separate generative processes in lamina 6 at different times after enucleation. Only the second of these processes appears to exist in lamina 5. It is proposed that these observations are compatible with the hypothesis that there is a diffuse, sparse projection of collaterals of retinal Y axons from one eye to more than one lamina of the lateral geniculate nucleus.