Staining in Histology refers to the process of applying coloured dyes or chemicals to biological tissues in order to enhance the visibility of specific structures under a microscope. The primary purpose of staining is to highlight different components of tissues, such as nuclei, cytoplasm, organelles, and extracellular matrix, making them easier to distinguish and study.
There are two main types of stains used in histology:
Routine or H&E Staining (Hematoxylin and Eosin): This is the most common staining method. Hematoxylin stains cell nuclei blue or purple, while eosin stains cytoplasm and other extracellular structures pink or red. This staining is often used for general examination of tissue morphology revealing the architectural organisation of cells, their size, shape, and distribution within a tissue.
Special Stains: These stains are designed to highlight specific components or structures within cells or tissues. Examples include periodic acid-Schiff (PAS) stain for glycogen, Masson’s trichrome stain for collagen, and immunohistochemical stains that use antibodies to detect specific proteins.
Staining is a scientific technique in histology as it allows pathologists to examine tissues and diagnose diseases based on the appearance of cells and structures. Different stains can provide information about tissue composition, cell types, and pathological changes, aiding in the understanding of normal and diseased tissues.