STAINING Flashcards
Three major Groups of Staining Tissues
- Histological staining
- Histochemical staining
- Immunohistochemical staining
Process whereby the tissue constituents are demonstrated in sections by direct interaction with a DYE or STAINING SOLUTION , producing coloration of the active tissue substance
Histological staining
Process whereby various constituents of tissues are studied through CHEMICAL REACTIONS that will permit microscopic localization of a specific tissue substance
Histochemical staining
Combination of immunologic and histochemical techniques that allow PHENOTYPIC MARKERS to be detected and demonstrated under the microscope using a wide range of polyclonal or monoclonal, fluorescent-labeled or enzyme-labeled antibodies
Immunohistochemical staining
METHODS OF STAINING:
- Direct staining
- Indirect staining
- Progressive staining
- Regressive staining
- Metachromatic staining
- Metallic impregnation
- Negative staining
- Counterstaining
- Vital staining
Process of giving color to the sections by using AQUEOUS or ALCOHOLIC DYE SOLUTIONS (ex. Methylene blue)
Direct staining
Process whereby the action of the dye is intensified by ADDING ANOTHER AGENT OR A MORDANT
Indirect staining
Serves as the LINK or BRIDGE between the tissue and the dye, to make the staining reaction possible
Mordant
Examples of mordant include:
- Phosphotungstic acid
- Iron
- Lead
- Aluminum
- Molybdenum
- Copper
What is the mordant of Harris hematoxylin?
Potassium aluminum
Accelerates or hastens the speed of the staining power and selectivity of the dye
Accentuator
The combination of a dye and a mordant
Lake
REMEMBER!
Direct staining - DO NOT USE MORDANT
Indirect staining - USES A MORDANT
Process whereby tissue elements are stained in a DEFINITE SEQUENCE and the staining solution is applied for specific periods of time or until the desired intensity of coloring of the different tissue elements is attained 9ex. Modified H&E stain)
Progressive staining
The tissue is first overstained to obliterate the cellular details, and the EXCESS STAIN IS REMOVED OR DECOLORIZED from unwanted parts of the tissue, until the desired intensity of color is obtained
Refressive staining
The most common method using the regressive staining which consists of overstaining the nuclei, followed by removal of excessive color of the tissue constituent by acid differentiation
ROUTINE HEMATOXYLIN AND EOSIN (H&E) STAINING
When using the regressive staining method, the nucleus is deliberately overstained with _______
Non-acidified hematoxylin
Selective REMOVAL OF EXCESS STAIN from the tissue during regressive staining
DIFFERENTIATION/DECOLORIZATION
Removal of UNWANTED ARTIFACTS during staining
WASHING-OUT
technique using specific dyes which differentiate particular substances by staining them with a color that is DIFFERENT FROM THE STAIN ITSELF
This is particularly employed for staining cartilage, connective tissue, epithelial mucins, mast cell granules, and amyloid
(ex. Toluidine blue: stains the mast cells purple)
METACHROMATIC STAINING
Specific tissue elements are demonstrated, not by stains, but by colorless solutions of METALLIC SALTS which are thereby reduced by the tissue, producing an opaque, usually black deposit on the surface of the tissue or bacteria; the most valuable metals for this purpose are GOLD (gold chloride) and Silver (silver nitrate)
Metallic impregnation
An acidic, anionic dye is used to change the color of the background, not the cells, causing the cells to stand out; this can be achieved by smearing the sample onto the slide and then applying NIGROSIN, a black synthetic dye or INDIA INK, an aqueous suspension of carbon particles
NEGATIVE STAINING
Application of a different color or stain to PROVIDE CONTRAST AND BACKGROUND to the staining of the structural components to be demonstrated
COUNTERSTAINING
REMEMBER!!
PROGRESSIVE vs REGRESSIVE
- Progressive staining WITHOUT differentiator/decolorizer and washing-out; ex: MODIFIED H&E stain
- Regressive staining WITH differentiator/decolorizer and washing-out; ex: ROUTINE H&E stain
REMEMBER!!
WASHING OUT
Fixation - washing out is removing excess fixative
Staining - washing out is removing unwanted artifiacts