carbohydrate stains Flashcards
what is the function of glycogen
energy
why is glycogen an important substance to be stained
only polysaccharide that survives fixation and processing
where is glycogen found
liver, muscle, endometrial glands, vaginal, and cervical epithelium
what are important groups of glycogen
cosist of branched or straight chains of D-glucose
most important functional group is the hydroxyl - hydroxyl adjacent , 1,2-glycols
what are mucins
heavily glycated proteins capable of forming gels
they form barrier, aid in cell signalling, lubrication of mucosal surfaces
acidic mucins are…
carboxylated or sulphated
neutral mucins are found in the…
GI systems
disease states in which glycogen is stained
lesions, tumors, and glycogenosis
disease states in which mucins are stained
tumors
are link secondary tumor to primary
histochemical methods for CHO
method that generate and demonstrate aldehydes
- periodic acid schiff
- grocott’s methenamine silver
what is a method that uses cationic dyes to demonstrate anionic groups
alcian blue
what is the PAS theory equations
adjacent glycol/amino hydroxy groups + periodic acid = aldehyde group
what is the staining procedure of PAS
- periodic acid: oxidation
- schiff’s reagent: washed extensively after
- hematoxylin: counterstain
what makes up schiffs reagent
basic fuschsin treated with sulphuric acid
- pseudo-leuco dye
what is the colors of schiff’s reagent
red - colourless - magenta
what are PAS positive substances
- glycogen
- neutral polysaccharides
- basement membrane
- neutral mucin
- starch
- cartilage
- fungi
- thyroid colloid
- goblet cells of GI tract
what can cause a false positive of PAS
-insufficient washing of schiffs or periodic acid
-coloured schiffs
-overexposure to periodic acid
what is grocott’s methanamine silver
- creation of aldehydes similar to PAS with a diff. oxidizing agent
- aldehydes groups can reduce silver
- used for the ID of fungi
steps in GMS
- chromic acid - generate aldehydes
- methanamine silver - control microscopically
- gold chloride - toning
- sodium thiosulfate - wash away unreduced silver
- light green - counterstain
what is alcian blue
a cationic dye that colours tissue at different pH
- method often combine with PAS which stains neutral mucins
alcian blue at ph 2.5 stains…
carboxyl and sulphate radicals of acidic mucus
alcian blue at pH 1.0 will..
only stain sulphate radicals
