An ultrastructural description of glutamate-like immunoreactivity in the rat cerebellar cortex

This study provides the first ultrastructural description of glutamate-like immunoreactive neurons and processes in the cerebellar cortex of the rat. Glutamate-like immunoreactivity was seen in parallel fibers, granule cell perikarya, Purkinje cell dendrites, and mossy fiber glomeruli. These data support previous studies that have suggested that granule cells may use glutamate as a neurotransmitter. However, not all granule cells or all parallel fibers were glutamate-like immunoreactive, suggesting that some granule cells may use transmitters other than glutamate. The presence of glutamate-like immunoreactivity in mossy fibers supports the hypothesis that some cerebellar afferent systems may use glutamate as a neurotransmitter.