Phosphotungstic acid haematoxylin (PTAH) is a mix of haematoxylin

Haematoxylin

Haematoxylin, hematoxylin, Natural Black 1, or C.I. 75290 is extracted from the heartwood of the logwood tree. When oxidized it forms haematein, a compound that forms strongly coloured complexes with certain metal ions, the most notable ones being Fe and Al salts. Metal-haematein complexes are used...

 with phosphotungstic acid

Phosphotungstic acid

Phosphotungstic acid , tungstophosphoric acid , is a heteropoly acid with the chemical formula 31240. It normally present as a hydrate. EPTA is the name of ethanolic phosphotungstic acid, its alcohol solution used in biology. It has the appearance of small, colorless-grayish or slightly...

, 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...

 for staining.

It stains some tissue in contrasting colors in a way similar to haematoxylin and eosin stain, as phosphotungstic acid binds to tissue protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s. It is used to show gliosis

Gliosis

Gliosis is a proliferation of astrocytes in damaged areas of the central nervous system . This proliferation usually leads to the formation of a glial scar....

 in the central nervous system

Central nervous system

The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

, tumours of skeletal muscle

Skeletal muscle

Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...

s, and fibrin

Fibrin

Fibrin is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot over a wound site....

 deposits in lesion

Lesion

A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

s. Muscle is stained blue-black to dark brown, 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...

 is pale orange-pink to brownish red, fibrin and neuroglia stain deep blue, coarse elastic fibers show as purple, 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...

 and cartilage

Cartilage

Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...

 obtain yellowish to brownish red color.

PTAH is ideal for demonstrating striated muscle fibers and mitochondria, often without a counterstain

Counterstain

A counterstain is a stain with color contrasting to the principal stain, making the stained structure more easily visible.An example is the malachite green counterstain to the fuchsine stain in the Gimenez staining technique....

. As such, it is used to identify contraction bands, as seen in contraction band necrosis

Contraction band necrosis

Contraction band necrosis is a type of uncontrolled cell death unique to cardiac myocytes and thought to arise in reperfusion from hypercontraction, which results in sarcolemmal rupture....

.

PTAH stains ependymomas while it does not stain choroid plexus papillomas, providing one means of differentiating these tumors.