Staining theory

Question 1

what is a dye

Answer 1

coloured substance that has affinity for a substrate

Question 2

what is a chromophore

Answer 2

structure that absorbs visible wavelengths of light causing delocalization of electrons

Question 3

T/F double and triple bonds are more delocalized than single bonds

Answer 3

T

Question 4

what is a chromogen

Answer 4

part of dye that contains chromophore

Question 5

what is an auxochrome

Answer 5

allows dye to attach to tissue by ionization

Question 6

what do anionic (acid) dyes contain

Answer 6

anionic auxochrome

Question 7

T/F categorization of acidic and basic dyes are based on their pH

Answer 7

F

Question 8

what chemical groups are anionic auxochromes

Answer 8

COOH
OH
SO3H

Question 9

what groups do anionic auxochromes bind to

Answer 9

positively charged tissue like lysine, histidine, and arginine

Question 10

what are common anionic dyes

Answer 10

eosin, orange G, Biebrich scarlet, acid fuchsin

Question 11

what chemical groups are cationic auxochromes

Answer 11

NH2

Question 12

what do cationic auxochromes bind to

Answer 12

negatively charged tissue like cartilage, granules, and mucins

Question 13

what are common cationic dyes

Answer 13

hematocylin
crystal violet
methylene blue

Question 14

what chemical group is yellow

Answer 14

nitro (NO2)

Question 15

what requirement does a dye need

Answer 15

auxochromes (COOH, OH, NH2)

Question 16

what is a mordant and what does it do

Answer 16

links the dye to tissue

Question 17

what is a dye lake

Answer 17

a dye with a mordant. eg hematoxylin

Question 18

what does an accentuator do

Answer 18

incrrease intensity of a dye

Question 19

what is a neutral dye

Answer 19

mix of acid and basic dyes eg. romanowsky

Question 20

what step is NOT used in progressive staining

Answer 20

differentiator NOT used

Question 21

what is regressive staining

Answer 21

overstained tissue is differentiated

Question 22

what is metachromasia

Answer 22

staining a different colour than the solution

Question 23

how does a metachromatic stain work

Answer 23

cationic dyes form aggregates with negatively charged sites in close proximity

Question 24

what substances stain metachromatic

Answer 24

mucins and amyloid

Question 25

what is polychromasia

Answer 25

solution contains several dyes to make many colours

Question 26

common polychromatic dye

Answer 26

methylene blue

Question 27

what are 3 chemiacl stianing mechanisms

Answer 27

covalent ionic hydrogen bonding

Question 28

what is covalent bonding

Answer 28

sharing of electrons eg schiff in PAS

Question 29

what is ionic bonding

Answer 29

attraction between unlike charges that are weaker than covalent but stronger than hydrogen bonding

Question 30

what will interfere with hydrogen bonding

Answer 30

water

Question 31

what stain uses hydrogen bonds

Answer 31

congo red for amyloid

Question 32

what are two physical staining mechanisms

Answer 32

selective solubility and porosity

Question 33

what is selective solubility

Answer 33

demonstrates lipids by migrating from solvent into tissue

Question 34

what is porosity

Answer 34

stains connective tissue as smallest dye applied first then bumped by larger dye

Question 35

what are vander waals forces

Answer 35

intermolecular attraction due to polarity

Question 36

what stain demonstrates vander waals

Answer 36

congo red

Question 37

what are histochemical stains

Answer 37

do not employ a dye or stain but use chemical reactions to form a color

Question 38

stain that demonstrates histochemical staining

Answer 38

perls prussian blue

Question 39

what silver staining methods are there

Answer 39

argentaffin argyrophil metallic substitution

Question 40

what is an argentaffin

Answer 40

substance that bind and reduce silver

Question 41

what are examples of argentaffin substances

Answer 41

melanin, formalin, and neurosecretory granules

Question 42

what in an argyrophil

Answer 42

bind but NO reduce silver reducing agent needed to help visualize the bound silver

Question 43

T/F argyrophil methods demonstrate argentaffin substancves

Answer 43

T

Question 44

examples of argyrophil substances

Answer 44

urates, granules, and reticulin fibers

Question 45

what is metallic substitution

Answer 45

silver will replace calcium and bright light is used to reduce the silver silver shown = calcium was present (indirect method)

Question 46

what stain uses metallic substiution

Answer 46

Von Kossa

Question 47

What happens if a chemical compound contains even numbers of cationic and anion groups

Answer 47

anionic always wins (shown in an iline blue)

Question 48

what stain uses the direct method of metallic substitution

Answer 48

alizarin red S stain

Question 49

why does Bouins fluid stain intensely compared to others

Answer 49

NO2 groups are mordants