Korean J Phys Anthropol.  2011 Dec;24(4):195-201.

Ribbon Synapses Formed at the Axon of the Calbindin-Immunoreactive ON Cone Bipolar Cell in OFF Sublamina of the Inner Plexiform Layer in the Rabbit Retina

• Koo TH
• Kim HL
• Jeon JH
• Jeong EJ
• Chun MH
• Moon JI
• Kim IB

Abstract

Some retinal neurons, including intrinsically photosensitive retinal ganglion cells have their dendrites stratified in sublamina a of the inner plexiform (IPL), the OFF sublayer, but paradoxically show light-driven ON electrophysiological responses. In order to understand the mechanism on this paradoxical response, by using immunoelectron microscopy with a specific antibody against calbindin, we examined the synaptic connections of the calbindin-immunoreactive ON cone bipolar cell of the rabbit retina, which is thought to make the ribbon synapse in sublamina a of the IPL. The ribbon synapses in sublamina a by calbindin-immunoreactive ON cone bipolar cells were mainly found at the border between the inner nuclear layer and the IPL. Interestingly, the output targets at these ribbon synapses turned out as monads, and multiple synaptic ribbons were engaged in each synapse. These findings were different from those at the conventional ribbon synapse formed by calbindin-immunoreactive ON cone bipolar axon terminals. Thus, these findings may be the characteristics of the calbindin-immunoreactive ON cone bipolar ribbon synapse in sublamina a and can be used to classify the synapse in the retinal circuit research.

Keyword

ON cone bipolar cell; Ribbon synapse; Synaptic circuitry; Electron microscopy; Rabbit retina

MeSH Terms

Axons
Calcium-Binding Protein, Vitamin D-Dependent
Dendrites
Microscopy, Electron
Microscopy, Immunoelectron
Presynaptic Terminals
Retina
Retinal Ganglion Cells
Retinal Neurons
Retinaldehyde
Synapses
Calcium-Binding Protein, Vitamin D-Dependent
Retinaldehyde