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Bipolar Cell Photoreceptors

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Abstract Bipolar cells serve as a direct pathway linking the ganglion cells and the photoreceptors. There are many different types of bipolar cells, the most common being rod and cone, but all of the cells are either ON or OFF types. The cells can be distinguished by glutamate receptor expression, response to light and in their structural layout. Bipolar cells responds to light when initiated by the synapses of photoreceptors. The neurotransmitter released by these photoreceptors is glutamate. The bipolar cells respond in two different ways to this stimulus, ON which is glutamate hyperpolarization and OFF which is glutamate depolarization. Retinal bipolar cells have voltage gated channels that lie within their membranes and take part in the voltage responses. The most common types of ions that pass through these channels are calcium and potassium. The three primary types of receptors are kainate, AMPA and NMDA. The AMPA receptors select for transient components of the light signal while the kainate receptors conduct sustained characteristics of the signal. This paper will review what role bipolar cells play in the transduction pathway of a light stimulus to the retina and the…show more content…
The axon terminal of rod bipolar cells are located next to ganglion cells but they do not touch. In the retina of mammals an amacrine cell called AII is the first intermediate in the transduction pathway of rod signals to ganglion cells (3). The AII cells conduct the signal by stimulating the cone bipolar cell process that takes place in the inner plexiform layer. This stimulation is achieved by either a chemical synapse with OFF cells or through the use of gap junctions that are located between AII dendrites and ON cone axons. The second intermediate in the transduction pathway to conduct signals from the rods to the ganglion cells are the cone axon
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