Staining theory

Question 1

Staining

Answer 1

visual labeling of an area of a tissue

Question 2

Chromophore

Answer 2

portion iof a dye molecule responsible for COLOUR

alternating double and triple bonds

Question 3

Chromogen

Answer 3

compound containing a choromophore

Question 4

auxochrome

Answer 4

attaces a chromogen to an area of interest

anions or cations form salts

Question 5

Anionic auxochromes

Answer 5

carboxyl (-COOH)
hydroxyl (-OH)
sulphonic (-SO3H)

Question 6

Cationic auxochrome

Answer 6

Amine (-NH2)

Question 7

Theory behind anionic auxochrome

Answer 7

Bind to positively charged tissue components

Amino groups, basic amino acids

Question 8

theory behind cationc auxochromes

Answer 8

bind negatively charged tissue components

phosphate groups (nucleus), sulfate groups (mucin, cartilage)

Question 9

Why are dyes used at a low pH?

Answer 9

Ionization and binding sites
auxochromes will be charged - bind to cationic dyes

Question 10

(4) methods of staining

Answer 10

1. ionic
2. size of molecule
3. fixation
4. van der Waals forces

Question 11

mordant

Answer 11

metal that binds dye to substrate

Question 12

tissue elements stain a different colour that the staining solution

Answer 12

metachromasia

property of the tissue

Question 13

what makes regressive staining different from progressive staining?

Answer 13

Differentiation/decolourization of excess dye

Question 14

physical staining

Answer 14

selective solubility
porosity

Question 15

tissue components are demonstated by a chemical reaction creating a coloured product

Answer 15

true histochemical

Question 16

Progressive staining

Answer 16

stain to desired intensity, stop stain

Question 17

regressive stain

Answer 17

tissue is overstained then differentiated until desired effect

Question 18

polychromasia

Answer 18

staining solution with different dye molecules

Staining property

Question 19

Argentaffin

Answer 19

Silver impregnation method - capable of reducing silver to its metallic form in solution

Question 20

Argyrophile

Answer 20

Silver impregnation method - not capable of reucing silver, requires an external reducing agent for visualization