The Internal Structure of the Nucleus geniculatus lateralis ventralis in the Avian Brain: A Golgi Study and Electron Microscopic Investigation.

Different types of neurons in the ventral geniculate nucleus of the thalamus of chicks were visualised by Golgi impregnation. The dendritic tree of projection neurons branched in a sphere-like territory in both the ventral and middle areas of the lamina externa. The dendrites of projection neurons in the lamina interna descended into the lamina externa and entered both the ventral and middle dendritic areas. One or two dendrites of the lamina interna neurons also emitted branches that developed a dorsal sphere-like dendritic territory. Optic terminals labelled by Golgi impregnation or injection of biotinylated dextran amine were found in these dendritic territories gathered into groups. They established synapses in these areas (synaptic islands or fields without a glial sheath) with different dendritic profiles, and a few gamma-aminobutyric acid (GABA)-positive terminals synapsed with them. No glomerulus-like synaptic complexes ensheathed by glial processes were found. Optic terminals also contacted the stem dendrites of projection neurons and GABA-positive neuron cell bodies and dendrites. Numerous synapses established by both optic and GABA-positive terminals were found on the proximal dendritic stems of the lamina interna projection neurons. Copyright © 2004 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]