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 geniculate 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 vesicles 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.