PAS response

PAS-stained preparation of a signet ring carcinoma of the stomach

PAS-stained preparation of candidiasis of the esophagus

The PAS reaction (abbreviation for periodic acid – Schiff reaction ) or incorrect PAS staining is a frequently used staining technique in histology . This results in the coloring of carbohydrates such as glycogen , cellulose , neutral mucopolysaccharides , mucoproteins and glycoproteins as well as glycolipids . These substances can be found, for example, in connective tissue fibers ( collagen ), basement membranes, cell walls ( glycocalyx ) and in neutral mucus (gastric mucus). Glycogen-rich cells can be found e.g. B. in the liver and in muscle tissue. In dermatology , it is used to detect PAS-positive microorganisms (fungi) as pathogens in the skin.

principle

By periodic acid , a strong oxidant , unsubstituted are glycol groups to two adjacent aldehyde oxidized. The Schiff reagent contains SCHIFF acid (colorless). Binding to the aldehyde groups leads to a molecular restructuring and the chromogenic property arises - clearly recognizable by the magenta color. In the next step, excess fuchsin sulphurous acid is differentiated by the sulphite rinse , removed and the color stabilized. A staining with hemalum (blue nuclei) or according to Van Gieson (VG) is used as a high-contrast nuclear staining .

The staining result includes a magenta-red to pink coloration of neutral mucopolysaccharides, blue-violet cell nuclei and pale pink or bluish colored cytoplasm at higher RNA concentrations .

Individual evidence

^ S. Baum: The PAS Reaction for Staining Cell Walls. In: CSH protocols. Volume 2008, No. 8, 2008, pp. Pdb.prot4956, PMID 21356881 .
^ WJ van der Laarse, P. van Noort, PC Diegenbach: Calibration of quantitative histochemical methods: estimation of glycogen content of muscle fibers using the PAS reaction. In: Biotechnic & histochemistry: official publication of the Biological Stain Commission. Volume 67, No. 5, September 1992, ISSN 1052-0295 , pp. 303-308, PMID 1300151 .
↑ G. Dubray, G. Bezard: A highly sensitive periodic acid-silver stain for 1,2-diol groups of glycoproteins and polysaccharides in polyacrylamide gels. In: Anal. Biochem. Tape. 119, No. 2, 1982, pp. 325-329, PMID 6176144 .

[1] S. Baum: The PAS Reaction for Staining Cell Walls. In: CSH protocols. Volume 2008, No. 8, 2008, pp. Pdb.prot4956, PMID 21356881 .

[2] WJ van der Laarse, P. van Noort, PC Diegenbach: Calibration of quantitative histochemical methods: estimation of glycogen content of muscle fibers using the PAS reaction. In: Biotechnic & histochemistry: official publication of the Biological Stain Commission. Volume 67, No. 5, September 1992, ISSN 1052-0295 , pp. 303-308, PMID 1300151 .

[3] G. Dubray, G. Bezard: A highly sensitive periodic acid-silver stain for 1,2-diol groups of glycoproteins and polysaccharides in polyacrylamide gels. In: Anal. Biochem. Tape. 119, No. 2, 1982, pp. 325-329, PMID 6176144 .