A light and electron microscopic study of GAT-1-positive cells in the cerebral cortex of man and monkey

Specimens of human cerebral cortex were obtained during neurosurgical opera tions and studied by immunocytochemistry and electron microscopy, using ant ibodies to the GABA transporter GAT-1. Cortical material from macaque monke ys was prepared similarly. Large numbers of GAT-1-positive non-pyramidal ne urons were observed in layers I, II, V, and VI of the cortex. Electron micr oscopy also showed that the GAT-1-positive axon terminals formed symmetrica l and not asymmetrical synapses, suggesting that they were the terminals of non-pyramidal neurons. Processes of cells in the walls of blood vessels we re also labelled. We conclude that GAT-1 is present in cell bodies and axon terminals of non-pyramidal neurons, and a population of mural cells in blo od vessels, in the primate cerebral cortex.