Staining

Staining is a biochemical process usually conducted to increase the contrast of a microscopic image.

  • Staining samples with different dyes is an important part of microscopy where the color contrast of a magnified is increased to differentiate the stained portion of the image from the rest.
  • Microscopic techniques in hematology, histopathology, and clinical microbiology use staining as a method to study and diagnose diseases at the microscopic level.
  • Dyes used in staining can be used to define the biological tissues, cell populations, or subcellular organelles.
  • The purpose of staining might also differ as some staining procedures are used to differentiate between two groups of microorganisms (Gram Staining) while some are used to observe motility and presence of a capsule.
  • Staining is a part of biochemistry where a class-specific dye is added to a substrate to qualify or quantify the presence of a certain compound.
  • Staining, however, is not limited to biological samples, as it can be used to study the lamellar structure of polymers and the structure of block compounds.
  • Bright field microscopes are commonly used to observe stained cells or other biological materials to provide a distinction between the sample and the background.
  • It is also difficult to observe colorless substances under a microscope, which is why the concept of staining is so popular.
  • Staining is of different types depending on their purpose; simple staining using a single stain to provide a contrast between the sample and the background; differential staining using more than one dyes in order to differentiate between cells or between organelles of a cell.
  • Among all the staining techniques, Gram staining is the most popular technique that are used to differentiate between Gram-positive and Gram-negative microorganisms.
  • Other staining techniques include endospore staining for endospores, acid-fast staining for fastidious organisms, Periodic-acid Schiff (PAS) for biomolecules, and Romanowsky staining to differentiate between blood cells.