[Electron microscopic and light microscopic studies of optical and cortical afferents in the lateral geniculate body, pars dorsalis, of albino rats with special attention to synaptic organization]

Abstract

1. In the CGLd of the albino rat there are to be found two forms of retinal terminals in electronmicroscopic investigations, they are identical with 2a and 2b terminals described formerly in Golgi-preparations. 2. The small 2b terminals are situated previously in the extraglomerular neuropil, which is identical with the terminal part of P-neuron dendrites. They establish asymmetric GRAYtype I contacts with dendrites and spines of the relay-cell-dendrites. 3. The large 2a terminals form filamentous contacts with the smooth surfaces of the dendrites of the stem-and branching-zones. Synaptic contacts (GRAY I) are established with the grape-like appendages in the branching zone of P-neuron dendrites. 4. In the glomeruli of the CGLd there are three main components, which are the nerve endings of large optic axons, the interneuron dendritic terminals and the relay-cell-dendrites. They are surrounded by astrocytic processes. 5. In the extra-glomerular neuropil there are numerous small nerve endings, they form GRAY type I contacts with relay-cell-dendrites and their spines. They are partly identical with the type I endings in Golgi-preparations (cortical terminals). 6. After the eye enucleation and ablation of the visual cortex the type 2a and 2b and type 1 terminals degenerate. There are two forms of degeneration, the light and the dark one. 7. After eye enucleation two forms of degenerations in the degenerating retinal axons occur, which are the "watery" and the "dense" form. Besides the astrocytes the oligodendrocytes remove the destroyed particles. 8. The ultrastructural characteristics of the interneuronal dendritic terminals and their possible funktion are discussed. 9. There is added a table of the synonyma of CGLd structures.