[Changes in the proximal axon segment in layer III pyramidal cells in the neocortex of aged humans. A Golgi study].

In the neocortex (in area 11) of the non-demented aged humans (average age: 72.6 years) preferably the pyramidal cells of layer III are subjected to a conspicuous aged-related alteration in that they develop spindle-shaped enlargements of their proximal axon segment. We found different degrees of these enlargements. A slender process arises distally from the dilatation showing the morphological characteristics of the axon. In Golgi impregnations, such layer III pyramidal cells with an axon alteration do not display obvious changes in the ramification or spine density of their dendrites.