1 Staining

• What is the principle of physical staining in histology?

  Dyes are dissolved or impregnated onto tissue
• How do physico-chemical stains work?

  They form intermolecular bonds with tissue
• What is an example of a physico-chemical stain?

  Hematoxylin & eosin

  
• What occurs during a histochemical staining process?

  A chemical reaction generates a new color
• What is the most commonly used staining technique?

  Hematoxylin-Eosin staining (H&E)
• What does hematoxylin stain in cells?

  It stains acidic cell components dark blue/purple

  
• What type of molecules does hematoxylin stain?

  Basophilic molecules like DNA and RNA
• What does eosin stain in cells?

  It stains basic cell components pink
• What color does PAS stain nuclei and carbohydrates?

  Nuclei blue and carbohydrates magenta
• What is the role of mucins in goblet cells?

  Mucins attract water and provide gel-like properties

  
• What is the composition of mucus?

  Mucins + H2O (95%)
• What is the thickness of the mucus layer in the human intestine?

  200 μm thick
• What are the main types of extracellular matrix (ECM) fibers?

  Collagen, elastic, and reticular fibers

  
• What is the primary protein in collagen fibers?

  Protein collagen
• What does Masson Trichrome stain?

  Collagen fibers blue or green, muscle red
• What does Van Gieson staining target?

  Collagen fibers in red, muscle yellow
• What color do elastic fibers stain with Verhoeff-van Gieson’s stain?

  Black
• What does GALLEGO stain differentiate?

  Elastic tissue from collagenous connective tissue
• What does silver staining target?

  Reticular fibers in black or brown
• What does Black Sudan stain?

  Stains lipids in black, nuclei red
• What does Oil Red O stain?

  Stains lipids in red
• What indicates a metachromatic reaction?

  A dye stains differently than its diluted solution
• What color do mast cell granules stain with toluidine blue?

  Purple-blue
• What do mast cells accumulate?

  Inflammatory mediators like histamine
• What does ZIEHL NEELSEN staining detect?

  Mycobacteria
• What does WARTHIN STARRY staining involve?

  Staining with silver ions
• What does PAS staining detect in fungi?

  Polysaccharide walls
• What is the basis of immunohistochemistry (IHC)?

  Use of antibodies to identify proteins
• What does immunofluorescence detect?

  Fluorescently labeled proteins or molecules
• What is the function of a fluorescence microscope?

  Labels specific proteins in samples
• How does a confocal fluorescence microscope improve resolution?

  Uses optical sectioning for better clarity