ULTRASTRUCTURAL ANALYSIS OF INDIVIDUAL LAYERS IN LATERAL GENICULATE BODY OF MONKEY

1. The cellular and synaptic pattern of the lateral geniculate body of the monkey has been studied electronmicroscopically by using microdissected portions from individual layers. For general orientation and comparison the Golgi technique has been utilised extensively. 2. This technique revealed four different types of neuron whose distribution differs in the various layers. The first type has 3-4 stem dendrites, which possess tiny side branches or appendages. The second type is smaller and has 8-10 stem dendrites. The third type is a Golgi type II cell with very long dendrites with bushy terminal arborisations. The fourth type are very small neurons and it is difficult to separate them from glial cells with certainty. 3. The synaptic organisation has been examined in great detail, in particular the different composition of the glomeruli in different layers. Seven components of a glomerulus have been found whose individual contributions vary in different layers. These components are: main axon, main dendrite, peripheral axons, peripheral dendrites, dendritic and axonal thorns and glia lamellae. 4. In addition to this synaptic pattern a further interesting synapse has been found, an axo-axonal type in contact with the initial segment of a large axon of a geniculate cell. © 1968 Springer-Verlag.