Due to their transparency, tissue samples' cellular and intracellular structures cannot be microscopically examined until dyes color them. Dyes are combined with other dyes and/or chemicals to make up stains. "Biologic stains" refer to dyes/dye complexes used to stain tissue samples for microscopic analysis in the histology laboratory.
Biological stains exist as:
- General tissue stains: Use 1 to 3 dyes to differentiate the nucleus from the cytoplasm of cells, such as hematoxylin and eosin (H&E).
- Special stains: These involve physical or sequent dyes combined by staining procedures to demonstrate specific structures within cells and tissue sections, such as connective tissue elements, often not shown by the H&E.
