Journal of Neuroscience, Vol 6, 1314-1324, Copyright © 1986 by Society for Neuroscience
Molecular specificity of defined types of amacrine synapse in cat retina
P Sterling and LA Lampson
The inner plexiform layer of cat retina contains synaptic structures
belonging to 50 or more types of "identified" neurons. To learn whether
there are antigens confined to subsets of these synaptic structures, we
raised monoclonal antibodies to homogenates of neural retina. Binding
patterns of these antibodies were visualized by the peroxidase-
antiperoxidase method and studied in serial, ultrathin sections by electron
microscopy. Four antibodies stained the synaptic varicosities of certain
amacrine cells. Many of the stained varicosities formed reciprocal synapses
with a rod bipolar axon terminal, but only about half of the reciprocal
synapses associated with a rod bipolar were stained. Other stained
varicosities formed synapses with cone bipolar axons, ganglion cell
dendrites, and unstained amacrine processes. The patterns were essentially
the same for each antibody and were not altered by staining with the
antibodies two at a time; therefore, it is likely that all four antibodies
stain the same subset of synaptic structures. These patterns would be
accounted for if there were staining of all the synaptic varicosities of
three of the four types of identified amacrine reciprocally connected to
the rod bipolar (A6, A8, A13). This localization suggests that the antigen
responsible for the binding pattern is not associated with synaptic
transmission. Staining is present in the inner plexiform layer during the
period of synaptogenesis and consequently the antibodies are serving as
markers for following the development of identified synapses in an
identified neural circuit.
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