The cone pedicle, a complex synapse in the retina

Neuron. 2000 Jul;27(1):85-95. doi: 10.1016/s0896-6273(00)00011-8.


Cone pedicles, the synaptic terminals of cone photoreceptors, are connected in the macaque monkey retina to several hundred postsynaptic dendrites. Using light and electron microscopy, we found underneath each cone pedicle a laminated distribution of dendritic processes of bipolar and horizontal cells. Superimposed were three strata of glutamate receptor (GluR) aggregates, including a novel layer of glutamate receptors clustered at desmosome-like junctions. They are, most likely, postsynaptic densities on horizontal cell dendrites. GABA(A) and GABA(C) receptors are aggregated on bipolar cell dendrites in a narrow band underneath the cone pedicle. Glutamate released from cone pedicles and GABA released from horizontal cell dendrites act not only through direct synaptic contacts but also (more so) through diffusion to the appropriate receptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dendrites / physiology
  • Dendrites / ultrastructure
  • Desmosomes / physiology
  • Electrophysiology
  • Immunohistochemistry
  • In Vitro Techniques
  • Intercellular Junctions / physiology
  • Macaca fascicularis
  • Microscopy, Confocal
  • Microscopy, Electron
  • Presynaptic Terminals / physiology
  • Presynaptic Terminals / ultrastructure
  • Receptors, GABA / metabolism
  • Receptors, Glutamate / physiology*
  • Retina / physiology*
  • Retina / ultrastructure
  • Retinal Cone Photoreceptor Cells / physiology*
  • Retinal Cone Photoreceptor Cells / ultrastructure
  • Synapses / physiology*
  • Synapses / ultrastructure
  • gamma-Aminobutyric Acid / metabolism


  • Receptors, GABA
  • Receptors, Glutamate
  • gamma-Aminobutyric Acid