What is an application method used for contrasting colors and backgrounds in staining?

Counterstaining is a method specifically used to provide contrast to tissues or cells that have already been stained with a primary stain. This technique involves applying a secondary stain, which binds to different cellular components or background elements than the primary stain. The purpose of counterstaining is to enhance the visibility of specific structures, allowing for better differentiation and examination under a microscope.

For example, if a tissue has been stained to highlight nuclei with a particular stain that colors those structures a deep color, a counterstain might be used to color the cytoplasm or the extracellular matrix in a complementary or contrasting color. This dual staining technique enables a clearer assessment of the tissue’s morphology and highlights pathological changes, which is particularly beneficial in histopathology.