Abstract
Bipolar cells play major roles in visual signal transmission from photoreceptors to ganglion cells, and can be further subdivided into at least 13 distinct types based on their morphology and physiology. Particularly, identification of the blue cone bipolar cell is an important work in color vision research. Color pathway has been studied for a long time in the primate, but the circuit for color processing in other mammals is still obscure, especially in the bipolar cell level. In this study, I was aiming to morphologically identify blue cone bipolar cells in the rabbit retina. For efficiently finding the blue cone bipolar cells, I used microinjection to mark bipolar cells, peanut agglutinin to label all cone cells, and anti-S cone opsin antibody to label S cone outer segments in the whole mount rabbit retina. I then superimposed the images to verify the cone selectivity in different injected bipolar cells. From the results of my experiments, each narrow-field and mediate-field type bipolar cells were showed to have no cone selectivity. However, there is one type of wide-field bipolar cells with S cone selectivity identified in my study. This type of cells gives rise 4-5 branchless primary dendrites to specifically contact S cone pedicles. In addition, there were also two other types of wide-field bipolar cells identified in my study, which have no S cone selectivity. In conclusion, the color encoding bipolar cells in rabbit retina are different from the ones found in primate retina. Therefore, the color information processing pathway of non-primate retina may be different from primate retina.