Neuronal composition and interneuronal connection of area 5 in the cat parietal association cortex.

Area 5 of the cat cortex was studied by Nissl's method and by Golgi's chromate-silver impregnation method. Its typical six-layered structure with well-developed layers of pyramidal cells was revealed. The characteristic features of area 5 are: predominance of pyramidal cells in layers II-III and the presence of large forms (40 x 26 mu) among them (in layer III); giant pyramidal neurons (70 x 23 mu) arranged singly or nidally in layer V; large (diameter 25-30 mu) and giant (diameter 40-45 mu) stellate cells with radial dendrites, arranged singly or in groups in layers V-VI; infrequent efferent fusiform neurons (40 x 20 mu) in layers V-VL Stellate cells connecting pyramidal neurons in the same or in different layers were found in layers II-VI. Some stellate cells in layers II-=III form long horizontal connections within area 5. Interneuronal connections are effected by axosomatic and axodendritic terminals, the latter being more numerous; Dendrodendritic and axoaxonal synapses are less common.