carbohydrate stains Flashcards

1
Q

what is the function of glycogen

A

energy

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2
Q

why is glycogen an important substance to be stained

A

only polysaccharide that survives fixation and processing

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3
Q

where is glycogen found

A

liver, muscle, endometrial glands, vaginal, and cervical epithelium

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4
Q

what are important groups of glycogen

A

cosist of branched or straight chains of D-glucose
most important functional group is the hydroxyl - hydroxyl adjacent , 1,2-glycols

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5
Q

what are mucins

A

heavily glycated proteins capable of forming gels
they form barrier, aid in cell signalling, lubrication of mucosal surfaces

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6
Q

acidic mucins are…

A

carboxylated or sulphated

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7
Q

neutral mucins are found in the…

A

GI systems

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8
Q

disease states in which glycogen is stained

A

lesions, tumors, and glycogenosis

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9
Q

disease states in which mucins are stained

A

tumors
are link secondary tumor to primary

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10
Q

histochemical methods for CHO

A

method that generate and demonstrate aldehydes
- periodic acid schiff
- grocott’s methenamine silver

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11
Q

what is a method that uses cationic dyes to demonstrate anionic groups

A

alcian blue

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12
Q

what is the PAS theory equations

A

adjacent glycol/amino hydroxy groups + periodic acid = aldehyde group

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13
Q

what is the staining procedure of PAS

A
  1. periodic acid: oxidation
  2. schiff’s reagent: washed extensively after
  3. hematoxylin: counterstain
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14
Q

what makes up schiffs reagent

A

basic fuschsin treated with sulphuric acid
- pseudo-leuco dye

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15
Q

what is the colors of schiff’s reagent

A

red - colourless - magenta

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16
Q

what are PAS positive substances

A
  • glycogen
  • neutral polysaccharides
  • basement membrane
  • neutral mucin
  • starch
  • cartilage
  • fungi
  • thyroid colloid
  • goblet cells of GI tract
17
Q

what can cause a false positive of PAS

A

-insufficient washing of schiffs or periodic acid
-coloured schiffs
-overexposure to periodic acid

18
Q

what is grocott’s methanamine silver

A
  • creation of aldehydes similar to PAS with a diff. oxidizing agent
  • aldehydes groups can reduce silver
  • used for the ID of fungi
19
Q

steps in GMS

A
  1. chromic acid - generate aldehydes
  2. methanamine silver - control microscopically
  3. gold chloride - toning
  4. sodium thiosulfate - wash away unreduced silver
  5. light green - counterstain
20
Q

what is alcian blue

A

a cationic dye that colours tissue at different pH
- method often combine with PAS which stains neutral mucins

21
Q

alcian blue at ph 2.5 stains…

A

carboxyl and sulphate radicals of acidic mucus

22
Q

alcian blue at pH 1.0 will..

A

only stain sulphate radicals