PAP

PAP or Periodic Acid-Schiff is a staining method used in histology. The method is used to detect polysaccharides such as glycogen, and mucosubstances such as glycoproteins, glycolipids and mucins in tissues. The reaction of periodic acid oxidizes the diol functional groups in these sugars, creating aldehydes that react with the Schiff reagent to give a purple-magenta color. A positive result indicates the presence of high amounts of carbohydrates in the tissue.

History

The PAP stain was developed by Alois Alzheimer in 1904. It was later modified by Jules Bordet and Octave Gengou, who added the Schiff reagent to the process.

Procedure

The procedure for PAP staining involves several steps. First, the tissue sample is fixed and dehydrated. Then, it is treated with periodic acid, which oxidizes the sugars in the tissue. The sample is then treated with the Schiff reagent, which reacts with the aldehydes to produce a purple-magenta color. The intensity of the color indicates the amount of carbohydrates in the tissue.

Applications

PAP staining is used in many areas of medicine and biology. It is commonly used in the diagnosis of certain diseases, such as Alzheimer's disease, where it can detect the presence of amyloid plaques in the brain. It is also used in the study of the liver, where it can detect the presence of glycogen and other carbohydrates.

See also

• Histology
• Staining (biology)
• Alzheimer's disease
• Liver

References

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