Carbohydrate Staining

Question 1

2 carbohydrates that are stained

Answer 1

Glycogen

Mucins

Question 2

What does glycogen presence on tissue mean?

Answer 2

Carcinoma on bladder, kidney, liver, ovary, pancreas etc

Question 3

What does neutral mucins presence on tissue mean?

Answer 3

Carcinoma stomach

Question 4

What does presence of sulphomucin on tissue mean?

Answer 4

Intestinal metaplasia of tissue (structure change)

Question 5

What does Periodic-Acid Schiff (PAS) stain?

Answer 5

Glycogen

Question 6

What is glycogen, where is it found?

Answer 6

Straight branches polysaccharide

Found on liver m, heart, skeletal muscle

Question 7

What can glycogen staining diagnose?

Answer 7

Tumours

Question 8

What does PAS stain?

Answer 8

Mainly glycogen membrane

Neutral acid - used combo with Alcian Blue

Question 9

PAS mechanism

Answer 9

Periodic Acid - oxidative cleavage of C-C of adjacent hydroxyl group (1,2-glycol) or with amino group

Forms schiff reactive dialdehyde groups

Schiff reagent made of:
(deep red) Fuschin-Sulphurous acid reacts with dialdehyde forming magenta compound
Schiff covalent bond with C2+3 = stuck between

More hydroxyl conc = deeper colour stain
Basement membrane - deep
Carb - pale

Haematoxylin can be counterstain for other tissue elements (nuclei)

Question 10

How is glycogen presence confirmed

Answer 10

Enzyme digest glycogen = loss of staining

Compare it to stained tissue without enzyme

Question 11

Alcian Dye properties

Answer 11

Different types (yellow, BLUE, green)

High molecular weight

Cationic (+ve) bind with carboxyl/sulphate group (-ve) on modified mucin

Can’t bind with phostohate groups (DNA)

Question 12

2 types of Mucins

Answer 12

Acid

Neutral

Question 13

Alcian Blue mechanism

Answer 13

Cationic (+ve) electrostatic bond with COO- or SO4-

Detect acid Mucins secreted by epithelial cells

Question 14

Alcian Blue - PAS combo

Answer 14

Alcian Blue - Acid Mucin

PAS - Neutral Mucin

Question 15

How does pH affect Alcian Blue staining

Answer 15

pH that fully ionises reactive group = intense staining

Different pH for Acid Mucins - Adv

Sulphate mucin = low pH

Carboxylate mucin = high pH

Question 16

Where are Acid mucins mainly found

Answer 16

Lung

Gut

Question 17

3 types of lipids

Answer 17

Simple

Compound

Derived

Question 18

What are simple lipids

Answer 18

Energy stores in adipose tissue

Fatty acid and alcohol ester

Fats, oil, wax

Question 19

What are compound lipids

Answer 19

Found in CNS

Fatty acid and alcohol with P/N group

Question 20

What are derived lipids

Answer 20

Hydrolysed fatty acids

Hormones, bile acids, inflammatory mediators, cholestestrol

Question 21

What destroys lipids in tissue in terms of tissue processing?

Answer 21

Alcohol, chloroform, xylene and paraffin

Question 22

Best way to process tissue with lipid?

Answer 22

Frozen sections - best for simple lipids

Fixate in neutral buffers - sectioning and staining

Question 23

Which dye is used for lipid staining

Answer 23

Sudan dyes

Question 24

2 types of Sudan dyes

Answer 24

Oil red o - frozen sections

Sudan black - lipid droplets

Question 25

Sudan dyes mechanism

Answer 25

Hydrophobic lipids affinity for Sudan dyes

Question 26

What does oil-red-o stain and what colour?

Answer 26

Stains frozen section lipids

Nuclei - Blue

Lipid - bright red/orange

Question 27

What does Sudan black dye and what colour?

Answer 27

Stains large lipid droplets in type I muscle fibres

Lipid - Black