A light and electron microscopic study of the visual cortex of the cat and monkey

Abstract A light and electron microscopic study has been made of areas 17, 18 and 19 of the cat and area 17 of the monkey(Macaca mulatta). An attempt has been made to clarify the somewhat confusing terminology applied to the laminar cytoarchitectonic pattern of the visual cortex. The cytoarchitectonic features of the subdivisions of the visual cortex of the cat and of area 17 of the monkey have been described. In both animals layer IV is characterized by the predominantly stellate nature of its cells. In the cat the stria of Gennari is situated in the upper part of layer IV and the extreme lower part of layer III, while in the monkey most of it is found outside layer IV, mainly in layer IIIc . There are other horizontally orientated axonal plexuses in layers I, III, V and VI. In Golgi material stellate cells can be classified as large and small 'smooth’, large and small 'spiny’ and small 'intermediate’. Stellate cells with large spines on long pedicles are particularly common in layer IV. A correlation has been made between the features of stellate and pyramidal cells in light and electron microscopic material, and the features of spine-bearing varicose dendrites derived from stellate cells described.