An electron microscopic comparison of the medial interlaminar nucleus and the a laminae in the dorsal lateral geniculate nucleus of the cat

The medial interlaminar nucleus (MIN) of the cat's dorsal lateral ge-niculate nucleus was studied under the light and electron microscopes and compared with the A laminae. At the light level, MIN has more axons and a lesser cell packing density than the A laminae. Examined at the electron microscopic level, MIN could not qualitatively be distinguished from the A laminae. When quantitative counts of the profiles containing synaptic ves-icles were made, MIN had less F profiles and more RSD profiles per unit area than the A laminae. Structure/function correlations suggest that additional F terminals may mediate nondominant eye inhibition and/or a greater amount of inhibition on X-cells versus Y-cells.