Abstract
Purpose: :
The wide–field bipolar cell in the rabbit retina is a sparsely populated cone bipolar cell type whose broad dendritic arbor does not contact all cones in its dendritic field. The purpose of our experiment was to identify its contacts with photoreceptors.
Methods: :
Wide–field bipolar cells were labeled by a vitreal injection of biocytin into each eye of an anesthetized rabbit. Fixed retinas (either sections or wholemounts) were reacted with ABC and fluorescein anti–avidin D to reveal the biocytin–labeled cells. Retinas were then triple labeled with antibodies against peanut agglutinin, red/green cone opsin or blue cone opsin to identify the cone types. The labeled tissue was imaged using a confocal microscope.
Results: :
Cone photoreceptors identified with an antibody to peanut agglutinin were double labeled with either red/green cone opsin or blue cone opsin but not both. The fraction of the blue cones to all cones was approximately 1:9 along the dorsal and ventral midline. The dendrites of the wide–field bipolar cells avoided cones labeled with red/green opsin and contacted all cones stained with blue cone opsin that were found within its dendritic field.
Conclusions: :
We conclude that the wide–field bipolar cell is the blue cone bipolar cell in the rabbit retina.
Keywords: bipolar cells • retinal connections, networks, circuitry • color vision