A study of Golgi preparations from the dorsal lateral geniculate nucleus of the adult cat

Abstract

Abstract Four cell types are distinguishable in the lateral geniculate nucleus. The largest (class 1) have their dendrites oriented in relation to the plane of the laminae. The dendrites cross laminar borders freely and bear many fine spines. Class 2 cells show less orientation of their dendrites. These dendrites bear clusters of grape‐like appendages close to the branching points and fine spines on their peripheral segments. Only the peripheral segments cross laminar borders. The smallest (class 3) cells have long stalked appendages and give rise to intrinsic axons which ramify close to the perikaryon. Cell classes 1 and 2 occur in laminae A and A1, with class 1 cells mainly concentrated between laminae. Class 3 cells occur in all major laminae. Class 4 cells, with long smooth dendrites oriented parallel to the lamina, lie in lamina B. Two types of extrinsic axon are seen. Type I axons give off many short simple terminal collaterals which often innervate more than one lamina. These are regarded as extra‐retinal afferents. Type II axons (probably retinal afferents) have complex flower‐like terminals and each axon innervates only one lamina. Contacts between several type II axons and two or more grape‐like clusters occur in laminae A and A1. In lamina B finer type II axons form complex overlapping terminal nests around the dendrites of class 4 cells.