Glycine is a major inhibitory neurotransmitter
in the mammalian retina and has been shown to influence
the responses of ganglion cells. Midget and parasol ganglion
cells serve distinct physiological roles in the primate
retina and show differences in their response characteristics
to light stimuli. In the present study, we addressed the
question of whether the expression of glycine receptors
differs in midget and parasol ganglion cells. Ganglion
cells in the retinae of marmoset and macaque monkeys were
injected with Neurobiotin in a live in vitro retinal
whole-mount preparation. Retinal pieces were then processed
with an antibody against the α1 subunit of the glycine
receptor. Strong punctate immunoreactivity indicative of
synaptic localization is present in the ON and OFF sublamina
of the inner plexiform layer. Many of the immunoreactive
puncta coincide with the dendrites of both midget and parasol
ganglion cells. Immunoreactive puncta are present on distal
and proximal dendrites of ON and OFF cells. These results
suggest that ON and OFF midget and parasol cells do not
differ with respect to the distribution of the α1 subunit
of the glycine receptor.