LECTURE - Carbohydrate Stains Flashcards
1
Q
where is glycogen found?
A
liver, muscle, endometrial glands, vaginal, and cervical epithelium
2
Q
only polysaccharide that survives fixation and processing (fine or coarse granules)
A
glycogen
3
Q
important functional group of glycogen
A
- hydroxyl
- adjacent hydroxyls = 1,2-glycols
4
Q
mucins
A
- heavily glycated proteins capable of forming gels
- barriers; cell-signaling; lubrication of mucosal surfaces
- acidic mucins are carboxylated or sulphated
- neutral mucins are found extensively in the GI system
5
Q
lesions, tumors, glycogenoses
A
glycogen
6
Q
tumors
link secondary tumor to primary
A
mucins
7
Q
methods that generate and demonstrate aldehydes
A
- periodic acid schiff
- Grocott’s methenamine silver
- methods that use cationic dyes to demonstrate anionic groups
= alcian blue
8
Q
Schiff’s reagent
A
- basic fuchsin (pararosaniline) treated with sulphuric acid
- red to colourless to magenta
- pseudo-leuco dye
- reagent should be discarded when it becomes coloured
9
Q
true leuco dye
A
colour - colourless - then back to initial colour
10
Q
PAS positive substances
A
- glycogen
- neutral polysaccharides
- basement membrane
- neutral mucin
- starch
- cartilage
- fungi
- thyroid colloid
- goblet cells of GI tract
- STAIN MAGENTA *
11
Q
non-specific PAS or false positives can occur if:
A
- insufficient washing after Schiff’s or periodic acid
- coloured Schiff’s
- overexposure to periodic acid
12
Q
Grocott’s methenamine silver
A
- creation of aldehydes similar to PAS, but with different oxidizing agent
- aldehydes groups can reduce silver (induced argentaffin)
- used for identification of fungi
13
Q
Alcian Blue
A
- cationic dye
- pH 2.5 = will stain carboxyl and sulphate radicals of acidic mucins
- pH 1.0 = only stain sulphate radicals
- often combined with PAS which stains neutral mucins
- steps Alcian blue, neutral red (counterstain)
