In the present study we examined the possible colocalization of the in
hibitory neurotransmitters glycine and GABA in the oculomotor nucleus
of the rabbit. Serial sections were processed alternately for glycine
and GABA postembedding immuno-cytochemistry. Ultrastructural analysis
revealed that all terminals that showed glycine-positive immunoreactiv
ity were also GABA positive; up to 5% of the GABA-positive terminals w
ere also glycine positive.