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Histology > Carbohydrate Stains - PAS, Alcian Blue, Toluidine Blue (Wk 7) > Flashcards

Carbohydrate Stains - PAS, Alcian Blue, Toluidine Blue (Wk 7) Flashcards

1
Q

This is the property of certain dyes which stain different colours depending on what tissue element they are attached to.

A

METACHROMASIA

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2
Q

Schiff’s effectiveness can be tested by adding a few drops to ________

A

formalin

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3
Q

This is the term for alcohol groups on adjacent carbons in a sugar molecule?

A

VICINAL DIOLS

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4
Q

This is what the D in PAS + D stands for.

A

DIASTASE

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5
Q

This value is one measurement of acid strength and is useful in determining at which pH anionic components will be ionized.

A

pKa

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6
Q

Schiff’s reagent binds to this reactive group

A

ALDEHYDES

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7
Q

3 important factors in metachromatic staining

A
  • pH
  • Water (dehydration will destroy metachromatic staining)
  • Spacing between anionic groups (0.3-0.5 nm spacing between groups; otherwise won’t stain)
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8
Q

Your spit contains this enzyme.

A

AMYLASE

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9
Q

This is one of the major types of mucosubstances and is found in connective tissues?

A

PROTEOGLYCANS

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10
Q

2 components in Mucicarmine?

A

aluminum + carmine

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11
Q

This is the name for an anionic group which will stain red-purple with Toluidine blue.

A

CHROMOTROPE

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12
Q

Schiff’s reagent may revert back to pararosaniline which is what colour?

A

pink

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13
Q

3 alternate stains for Alcian blue

A
  • Mucicarmine
  • Colloidal iron
  • Lectins
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14
Q

The carbohydrate component of a proteoglycan is called?

A

Glycosaminoglycan

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15
Q

Glycoproteins can be removed by using..?

A

Neuraminidase

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16
Q

Why must Alcian blue/PAS be done in a particular order, and what that order is?

A

Alcian before PAS

Schiff’s will introduce sulphonic acid groups = false positives if stained w/ Alcian

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17
Q

Chromophore in pararosaniline?

A

Quinoid ring

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18
Q

When this kind of a chemical group is ionized it can be stained with Alcian blue at pH 2.5 but not at pH 1.0?

A

CARBOXYLIC ACID

19
Q

2 types of carbohydrates that stain with Alcian Blue

A

Proteoglycans

Acid glycoproteins (NOT neutral)

20
Q

The name for HIO4

A

PERIODIC ACID

21
Q

This is the most common dye used to demonstrate amyloid.

A

CONGRO RED

22
Q

Proteoglycans can be removed by using..?

A

Hyaluronidase

23
Q

These mucosubstances are considered to be epithelial mucins.

A

GLYCOPROTEINS

24
Q

Why is pararosaniline a PSEUDOLEUCO dye?

A

Colourless (due to addition of SO3- to chromophore) and colour is re-established in presence of aldehydes

Not a true leuco dye b/c doesn’t involve redox rxn

25
Q

Why is pararosaniline preferred over basic fuchsin to make Schiff’s reagent

A

Basic fuchsin is a MIXTURE of dyes

Pararosaniline is a SINGLE dye (better specificity)

26
Q

General description of dyes which can be used to demonstrate acid mucins and other negatively charged components?

A

CATIONIC

27
Q

This is the pH at which only sulphated proteoglycans will stain.

A

pH 1.0

28
Q

Modern Schiff’s reagent is made from this single dye

A

Pararosaniline

29
Q

Repetitive anionic groups responsible for metachromatic staining

A

Chromotropes

30
Q

Purpose of staining at pH 1.0 and 2.5 for Alcian blue?

A

Differentiate between sulphate and carboxylated mucins (via none/increase in staining intensity)

COOH only stains at 2.5

31
Q

This dye will specifically demonstrate Cryptococcus neoformans.

A

MUCICARMINE

32
Q

This simple sugar is rarely seen in human tissues due to its solubility.

A

GLUCOSE

33
Q

What functional group gets attached to carbohydrates after the addition of Schiff’s reagent?

A

SO3H

34
Q

PAS is an example of a staining method that works via __________ bonding

A

covalent

35
Q

2 potential false positives in PAS due to the oxidation step?

A
  • Glutaraldehyde-fixed tissues

- Some lipids

36
Q

The liver would be one place to find this mucosubstance.

A

GLYCOGEN

37
Q

PAS stain will demonstrate neutral mucins located in ______________ of liver

A

portal triads

38
Q

This is a mucosubstance which is often linked to proteins in glycoproteins?

A

SIALIC ACID

39
Q

Used to detect aldehydes?

A

SCHIFFS REAGENT

40
Q

How is the chromophore in pararosaniline modified?

A

Destroyed by addition of SO3- to form colourless solution

41
Q

4 main PAS(+) substances

A
  • Glycogen
  • Neutral glycoproteins (stomach)
  • Neutral glycoproteins (SI)
  • Basement membranes
42
Q

Why don’t proteoglycans stain PAS-positive?

A

Periodate ion (HIO4-) is repelled by COO- and SO3- parts of proteoglycan = no oxidation

43
Q

Oxidizing agent in PAS stain

A

Periodic acid

44
Q

This is a term for anisotrophic substances.

A

BIREFRINGENT

Histology (18 decks)

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