GLYCOL METHACRYLATE EMBEDDING AND MICROWAVE STAINING FOR LIGHT-MICROSCOPY OF THE MOUSE COCHLEA

This study examined the utility of a methacrylate-based embedding medi um and microwave staining for light microscopic quantification of hair cells and spiral ganglion cells in the mouse cochlea. The most import ant phase of the preparation process involved slowing down the polymer ization process. The tissue molecules so locked within the plastic mat rix produced excellent preservation of the organ of Corti and adjacent structures including the spiral ganglion, as well as tissue ionic cha rges. Excitable by microwaves, these ionic charges accelerated the mov ement of the basic dye (hematoxylin) into the tissue, reducing the tim e for this segment of the staining process from approximately 45 minut es to 1-2 minutes. When embedded in glycol methacrylate (GMA), acidic dyes show less stain-cell affinity so that staining intensity and time cannot be improved significantly. However, addition of color extender s to the counterstain eosin produced distinguished staining of all tis sue constituents. Thus, a combination of GMA embedding medium, use of the microwave for staining and addition of color extenders to the coun terstain generated excellent structural resolution and contrast. This made both hair cell and spiral ganglion cell counts possible from with in the same specimen and provided an opportunity for qualitative evalu ation as well.