Pyramidal Cells and Neuropil of Layer II

Abstract

Layer II is densely populated with small neurons, and its lower margin is difficult to determine (Fig. 10). Most of the neurons are small pyramidal cells. Intermingled with both nonpyramidal and glial cells, they tend to aggregate in clusters, triads, horizontal rows, and vertical columns (Fig. 11a—c). The narrow cytoplasmic rim of the small pyramidal cell (diameter 8–11 μm) is faintly tinged. At the origin of the apical dendrite a more pronounced basophilic area is visible (Fig. 11a, b). The apical dendrite (diameter 2.5 μm) can be traced for about 15 μm. Often both the perikaryon and the apical dendrite are associated with a satellite glial cell (Fig. 1la, b; see also Von Economo and Koskinas 1925).