What is a metachromatic dye?

What is a metachromatic dye?

A dye—e.g., methylene blue, toluidine blue, safranine—capable of staining tissues with colours that differ from the dye itself.

What is metachromasia staining?

Metachromasia may be defined as the staining of tissue or tissue components such that the color of the tissue-bound dye complex differs significantly from the color of the original dye complex to give a marked contrast in color (Pearse 1960).

What is metachromasia give an example?

For example, toluidine blue becomes dark blue (with a colour range from blue-red dependent on glycosaminoglycan content) when bound to cartilage. Other widely used metachromatic stains are the haematological Giemsa and May-Grunwald stains that also contain thiazine dyes.

Why is metachromatic stain used?

Metachromatic staining is important in the detection of mast cells and is strongly recommended as a routine stain for this purpose. One of the most frequently metachromatic stains is toluidine blue which stains the mast cell granules purple-to-red (Fig. 1).

Is methylene blue metachromatic?

Methylene blue does not possess the necessary HC1 grouping, and so Michaelis classified it as a non-metachromatic dye.

What do you mean small of metachromasia?

Medical Definition of metachromasia 1 : the property of various tissues of staining in a different color (as when treatment with a blue aniline dye makes a cellular element red) 2 : the property of various biological stains that permits a single dye to stain different tissue elements in different colors.

What do you mean by metachromatic reaction?

Metachromasia takes place when certain negatively charged groups on the tissue react with cationic dyes. On polymerization the original colour of the dye changes to another colour (eg mast cell stain pink with toluidine blue). Page 2. 79. Metachromatic Staining.

Is Crystal Violet a metachromatic dye?

Crystal violet is a degradation product of methyl green, so this dye has also been used for metachromatic amyloid staining and gives purple-red amyloid on a green background, thus increasing contrast.

What are the metachromatic granules?

Volutin granules (metachromatic or Babes-Ernst granules) are highly refractive, strongly basophilic bodies consisting of polymetaphosphate. They appear reddish when stained with polychrome methylene blue or toluidine blue (metachromasia).

What causes the shift in Colour change in metachromasia?

The tissue element reacting in this manner are said to be exhibiting metachromasia. The generally accepted explanation of this phenomenon is that change in color is due to polymerization. Sulfated substances are highly metachromatic e.g. Mast cell granules.

What type of dye is safranin?

cationic dye
Safranin is a basic biological dye commonly used as a counter-stain in some of the staining protocols like gram staining. Safranin is a cationic dye used in histology and cytology to distinguish and identify different tissues and cells.

What is the difference between crystal violet and gentian violet?

The name gentian violet was originally used for a mixture of methyl pararosaniline dyes (methyl violet), but is now often considered a synonym for crystal violet. The name refers to its colour, being like that of the petals of certain gentian flowers; it is not made from gentians or violets.

Why are the granules named metachromatic?

Volutin granules, sometimes termed metachromatic granules because of their colour reaction with the dyes used in light microscopy, contain polymerized inorganic phosphate, an energy-rich compound that acts as a reserve store of energy and of phosphate.

What are the other names of metachromatic granules?

Volutin granules (metachromatic or Babes-Ernst granules) are highly refractive, strongly basophilic bodies consisting of polymetaphosphate.

Why safranin is called counterstain?

A counterstain, such as the weakly water soluble safranin, is added to the sample, staining it red. Since the safranin is lighter than crystal violet, it does not disrupt the purple coloration in Gram positive cells. However, the decolorized Gram negative cells are stained red.

What is another name for crystal violet?

Crystal violet or gentian violet, also known as methyl violet 10B or hexamethyl pararosaniline chloride, is a triarylmethane dye used as a histological stain and in Gram’s method of classifying bacteria.