Stability of the neuronal population of the dorsal lateral geniculate nucleus (LGNd) of aged rats.

The variations, with aging, of both neuronal and glial populations of the rat LGNd have been studied quantitatively. Our results show a stability of the total number of neurons of the rat LGNd with aging; this, plus the constant increase of the rat LGNd volume throughout rat life, causes the neuronal density to decrease slowly. Our data prove the necessity of determining the total number of neurons, not just neuronal density, in order to find out the actual evolution of the neuronal population with aging. Both glial cell number and density show an increase throughout rat life.