AbstractLong‐term transneuronal changes have been investigated in the lateral geniculate nucleus of the squirrel monkey (Saimiri sciureus). Recent reports that the parvocellular portion of that nucleus is laminated in typical primate fashion are verified. Measurements of changes in cell size indicate that, (a) cells in the parvocellular layers show greater shrinkage than do cells in the magnocellular layers and, (b) there is little change in cell size for enucleation terms of one versus two years. Measurements are also presented which suggest that lateral geniculate cells retaining retinal input in the monocular squirrel monkey show an increase in cross‐sectional area so that enucleation may lead to both atrophic and hypertrophic chan