Masson's trichrome is a three-colour staining

Staining (biology)

Staining is an auxiliary technique used in microscopy to enhance contrast in the microscopic image. Stains and dyes are frequently used in biology and medicine to highlight structures in biological tissues for viewing, often with the aid of different microscopes...

 protocol used in histology

Histology

Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...

. The recipes evolved from Claude L. Pierre Masson's original formulation to different specific applications, but all are suited for distinguishing cells

Cell (biology)

The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....

 from surrounding connective tissue

Connective tissue

"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...

.

Most recipes produce red keratin

Keratin

Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...

 and muscle fibers, blue or green collagen

Collagen

Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...

 and bone

Bone

Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...

, light red or pink cytoplasm

Cytoplasm

The cytoplasm is a small gel-like substance residing between the cell membrane holding all the cell's internal sub-structures , except for the nucleus. All the contents of the cells of prokaryote organisms are contained within the cytoplasm...

, and dark brown to black cell nuclei

Cell nucleus

In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...

.

The trichrome is applied by immersion of the fixated sample into Weigert's iron hematoxylin, and then three different solutions, labeled A, B, and C:

• Weigert's hematoxylin is a sequence of three solutions: ferric chloride in diluted hydrochloric acid
  Hydrochloric acid
  Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
  
  , hematoxylin in 95% ethanol
  Ethanol
  Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
  
  , and potassium ferricyanide
  Potassium ferricyanide
  Potassium ferricyanide is the chemical compound with the formula K3[Fe6]. This bright red salt contains the octahedrally coordinated [Fe6]3− ion. It is soluble in water and its solution shows some green-yellow fluorescence.-Preparation:...
  
   solution alkalized by sodium borate. It is used to stain the nuclei.
• Solution A, also called plasma stain, contains acid fuchsin, Xylidine Ponceau
  Ponceau 2R
  Ponceau 2R, Xylidine ponceau, Ponceau G, Red R, Acid Red 26, Food Red 5, or C.I. 16150 is a red azo dye used in histology for staining. It is easily soluble in water and slightly in ethanol...
  
  , glacial acetic acid, and distilled water
  Distilled water
  Distilled water is water that has many of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container.-History:...
  
  . Other red acid dyes can be used, e.g. the Biebrich scarlet
  Biebrich scarlet
  Biebrich scarlet is a molecule used in Lillie's trichrome....
  
   in Lillie's trichrome.
• Solution B contains phosphomolybdic acid
  Phosphomolybdic acid
  Phosphomolybdic acid, also known as dodeca molybdophosphoric acid or PMA is a component of Masson's trichrome stain. It is a yellow-green compound, freely soluble in water and polar organic solvents such as ethanol...
  
   in distilled water.
• Solution C, also called fibre stain, contains Light Green SF yellowish
  Light Green SF yellowish
  Light Green SF yellowish, or Light Green, Acid Green, Lissamine green SF, Acid Green 5, Food Green 2, FD&C Green no. 2, Green No. 205, Acid Brilliant Green 5, Pencil Green SF, or C.I. 42095, is a green triarylmethane dye. It is used in histology for staining collagen; for that purpose it is a...
  
  , or alternatively Fast Green FCF
  Fast Green FCF
  Fast Green FCF, also called Food green 3, FD&C Green No. 3, Green 1724, Solid Green FCF, and C.I. 42053, is a sea green triarylmethane food dye. Its E number is E143....
  
  . It is used to stain collagen. If blue is preferred to green, methyl blue
  Methyl blue
  Methyl blue, also known as Cotton blue, Helvetia blue, Acid blue 93, or C.I. 42780, is a chemical compound with the molecular formula C37H27N3Na2O9S3. It is used as a stain in histology. Methyl blue stains collagen blue in tissue sections. It is soluble in water and slightly soluble in ethanol...
  
  , water blue
  Water blue
  Water blue, also known as aniline blue, Acid blue 22, Soluble Blue 3M, Marine Blue V, or C.I. 42755, is a chemical compound used as a stain in histology. Water blue stains collagen blue in tissue sections...
  
   or aniline blue can be substituted.

Variants

A common variant is Lillie's trichrome

Lillie's trichrome

Lillie's trichrome is a combination of dyes used in histology.It is similar to Masson's trichrome stain, but it uses Biebrich scarlet for the plasma stain.-External links:* at StainsFile.info...

. It is often erroneously called Masson's trichrome. It differs in the dyes used, their concentrations, and the immersion times.

Another common variant is the Masson trichrome & Verhoeff stain, which combines the Masson trichrome stain and Verhoeff stain. It is sometimes just referred to as a Masson trichrome . A reference is needed for the previous statement, since the Masson's trichrome method on its own does not stain elastin fiber black. This combination is useful for the examination of blood vessel

Blood vessel

The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

s; the Verhoeff stain highlights elastin

Elastin

Elastin is a protein in connective tissue that is elastic and allows many tissues in the body to resume their shape after stretching or contracting. Elastin helps skin to return to its original position when it is poked or pinched. Elastin is also an important load-bearing tissue in the bodies of...

(black) and allows one to easily differentiate small arteries (which typically have two elastic laminae) and veins (which have one elastic lamina).

External links

• Stainsfile: Masson's Trichrome
• Masson's Trichrome Protocol