Cell-specific markers for the identification of retinal cells by immunofluorescence microscopy

Identification and visualization of specific cells and cellular structures in the retina are fundamental for understanding the visual process, retinal development, disease progression, and therapeutic intervention. The increased usage of transgenic and naturally occurring mutant mice has further emphasized the need for retinal cell-specific imaging. Immunofluorescence microscopy of retinal cryosections and whole mount tissue labeled with cell-specific markers has emerged as the method of choice for identifying specific cell populations and mapping their distribution within the retina. In most cases indirect labeling methods are employed in which lightly fixed retinal samples are first labeled with a primary antibody targeted against a cell-specific protein of interest and then labeled with a fluorescent dye-tagged secondary antibody that recognizes the primary antibody. The localization and relative abundance of the protein can readily be imaged under a conventional fluorescent or confocal scanning microscope. Immunofluorescence labeling can be adapted for imaging more than one protein antigen through the use of multiple antibodies and different, nonoverlapping fluorescent dyes. A number of well-characterized immunochemical markers are now available for detecting photoreceptors, bipolar cells, amacrine cells, horizontal cells, Müller cells, and retinal pigment epithelial cells in the retina of mice, and other mammals.