A light and electron microscopic study of GluR4-positive cells in human cerebral cortex.

In human cerebral cortex non-pyramidal neurons were densely labelled for the glutamate receptor subunit GluR4, but pyramidal cells only lightly. Some small glial cells were also positive. They were either 'non-activated', with thin processes, or 'activated', with thicker stem processes with irregular outlines due to the presence of surface projections, and containing phagocytosed neuronal debris. GluR4-positive glia are putatively identified as oligodendrocyte precursor-like cells, and have similar light microscopic features to NG2 chondroitin sulphate proteoglycan-positive cells [Levine, J.M.,J. Neurosci., 14 (1994) 4716-4730].