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7 Cards in this Set
- Front
- Back
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PAS Stain Preferred: Fixative, QC Tissue, Section thickness |
10%NBF or Bouin. Blood Smears Methyl alcohol.
PS:4-5um (kidney 1-2um)
Kidney(most sensitive), Liver, Cervix |
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PAS Main Reagents |
Periodic Acid 0.5% Solution Schiff Reagent 0.55% Potassium Metabisulfite Harris Hematoxylin |
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PAS demonstrates what? |
Neutral Polysaccharides like glycogen & chitin (found in fungal cell walls).
Neutral glycoproteins/mucoprotein/mucosubstances like epithelial mucins.
Also basement membranes, colloid material of the thyroid, & pars intermedia of the pituitary.
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What is the purpose of the Metabisulfite rinse in PAS stain |
To remove any uncombined leucofuchsin following Schiff Reagent which could result in nonspecific staining if loosely adsorbed Schiff Reagent were to be reoxidized by highly chlorinated water to basic fuchsin. |
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Can fungi be demonstrated with PAS? If so, with what counterstain? |
0.02% Fast Green Counterstain with 1drop acetic acid for every 60mL. |
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What fixative reagent(s) are not recommended for PAS? Why? |
Glutaraldehyde. Has 2 aldehydes & 1 remains available for to react with Schiff reagent causing false positive results.
Chromate-containing fixatives can overoxidize reactive groups resulting in weak rxns with Schiff reagent. |
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What is necessary for color development in PAS Stain? |
Washing in tap water after sulfite rinses. |
