An electron microscopic and morphometric study on the GABA-immunoreactive terminals in the cuneate nucleus of the rat.

Immunogold labelling was used to identify GABA-immunoreactive (GABA-IR) terminals in the cuneate nucleus of the rat. About 30% of the terminals surveyed were GABA-IR. They were mostly small, although a few of medium size were encountered. The terminals contained either polymorphic or round synaptic vesicles; these occurred in an approximately 5:1 ratio. Most of these terminals formed symmetric synapses with dendrites of various sizes. The GABA-IR terminals also made synaptic contacts with somata of cuneate neurons and axon terminals of unknown origin. In addition, a few GABA-IR terminals forming asymmetric synapses were found in the cuneate neuropil. The possible functional significance of the synaptic organisation is discussed.