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
Farlex Partner Medical Dictionary © Farlex 2012


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.
Medical Eponyms © Farlex 2012

per·i·od·ic ac·id-Schiff stain

(PAS) (pērē-odik asid shif stān)
A clinical tissue-staining procedure.
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
This, associated with the histochemical characteristics obtained through the AB and PAS stains, are typical of fungi of the Cryptococcus genus (GUARNER & BRANDT, 2011; RIET-CORREA et al., 2011; GALIZA et al., 2014).
We identified information pertaining to 541 onychomycosis-associated toenail specimens sent for PAS stain, of which 160 (29.6%) were sent by dermatologists, 198 (36.6%) by podiatrists, and 183 (33.8%) by other provider types.
Caption: FIGURE 4: (a) PAS stain of the retinochoroidal biopsy demonstrates septate filamentous fungi with acute angle branching consistent with Aspergillus fumigatus.
The histopathology of the nail clippings sample treated with a PAS stain demonstrates fungal elements and is the most sensitive test, but it does not identify the species.
The PAS stain performs almost as well as GMS, in screening for fungi.
(c) Diastaseresistant eosinophilic globular inclusions, PAS stain with diastase.
Caption: Figure 4: Nodular-to-diffuse, pyogranulomatous panniculitis with numerous Prototheca-Hke elements stained vividly purple with PAS stain.
Visualization of the yeasts on 10% KOH preparation, Gomori's stain, PAS stain, or Papanicolaou's smear of tissue biopsy, tracheal aspirates, BAL fluid, and sputum specimens or tissue cytological analysis or fungal culture on Sabouraud dextrose agar at room temperature are some basic methods for diagnosis of the Blastomyces dermatitidis infections.
Providing a history and the physical characteristics of the rash or a differential diagnosis will prompt the performance of a PAS stain. Otherwise, the diagnosis can be missed because fungal elements are often not visible on routine H&E stains.
PAS stain further identified ribbon like, non-septate hyphae along with developing spores (Figures 6).
The normal liver contains a large amount of glycogen, leading to hepatocytes staining intensely pink with a PAS stain. Figure 1(a) shows that HepaRG cells stain strongly pink with PAS staining, indicative of high glycogen content, whereas HepG2 cells stain much less strongly for glycogen, with the blue nuclear counter stain dominating (Figure 1(a)).
Parenchymal staining was less intense for NS than the PAS stain, though the vitellarium stained intensely with NS.