Mode of termination of afferents from the thalamic reticular nucleus in the dorsal lateral geniculate nucleus of the rat.

The terminals of axons projecting to the dorsal lateral geniculate nucleus from the thalamic reticular nucleus were identified by electron microscopy 8-24 h after placing small lesions in the ipsilateral reticular nucleus. The terminals contained flattened synaptic vesicles and made Gray type II axo-dendritic synaptic contacts with geniculate neurons. Their identification as F-axons accords well with physiological evidence for a powerful monosynaptic inhibitory input to geniculocortical projection cells from reticular nucleus neurons.