periodic acid-Schiff stain

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per·i·od·ic ac·id-·Schiff stain (PAS),

a tissue-staining procedure in which 1,2-glycol groupings are first oxidized with periodic acid to aldehydes that then react with the sulfite leucofuchsin reagent of Schiff and turn red-violet; strong staining occurs with polysaccharides, such as glycogen, and mucopolysaccharides of epithelial mucins, basement membranes, and connective tissue.
Synonym(s): PAS stain


Hugo, German chemist in Florence, 1834-1915.
Kasten fluorescent Schiff reagents - see under Kasten
ninhydrin-Schiff stain for proteins
periodic acid-Schiff stain - a tissue-staining procedure. Synonym(s): PAS stain
Schiff base - condensation products of aldehydes and ketones with primary amine. Synonym(s): aldimine
Schiff reagent - used for aldehydes and in histochemistry to detect polysaccharides, DNA, and proteins.

per·i·od·ic ac·id-Schiff stain

(PAS) (pērē-odik asid shif stān)
A clinical tissue-staining procedure.
References in periodicals archive ?
Psammomatous calcification (A) and periodic acid-Schiff stain positive hyaline bodies (B) were seen in the tumour stroma (arrowed) (x100).
Tinea faciei can induce a psoriasiform as well as a spongiotic reaction pattern, and therefore, a periodic acid-Schiff stain is appropriate in this setting as well.
There were numerous yeastlike organisms seen with this stain but not with the periodic acid-Schiff stain.
A periodic acid-Schiff stain indicated absence of glycogen deposits.
Periodic acid-Schiff stain failed to demonstrate glycogen particles in the cytoplasm of the cells.
3,4) Mucicarmine and periodic acid-Schiff stain the characteristic thick mucopolysaccharide capsule.
Periodic acid-Schiff stain demonstrated the presence of positive granules in the cytoplasm of nucleated red blood cells and some blasts (Figure 2).
Mucicarmine stain was negative and periodic acid-Schiff stain was positive and seen decorating the cell membrane.
A periodic acid-Schiff stain was focally positive, and the positivity was abolished by diastase digestion.
Acid-fast bacilli and periodic acid-Schiff stains were negative.
Periodic acid-Schiff stains demonstrated occasional yeast cells thought to be Pityrosporum.

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