WEEK 3: Common stains in cellular pathology

Question 1

generally, what colour are parts of the cell stained in a H&E stain?

Answer 1

nuclei is black/blue, and everything else is red/pink

Question 2

what charge does a nuclei acid have?

Answer 2

negative

Question 3

in H&E, which dye do nuclei acids react with? What colour is produced?

Answer 3

reacts with haematoxylin and turns blue

Question 4

what gives a positive charge in the body?

Answer 4

cytoplasm, muscle, collagen

Question 5

does eosin react with positive or negative compartments?

Answer 5

positive

Question 6

H+E. Which is positive and which is negative dye?

Answer 6

haematoxylin is positive and eosin is negative

Question 7

what colour does eosin stain?

Answer 7

red/pink

Question 8

what colour do RBCs give after H+E stain?

Answer 8

orange

Question 9

what 2 dyes is Van Gieson’s stain composed of?

Answer 9

acid fuchsin and picric acid

Question 10

what is the principle of Van Gieson’s stain?

Answer 10

Picric acid, small molecules, penetrate all the tissue rapidly, but are only firmly retained in the close textured red blood cells and muscle.
Acid fuchsin, larger molecules, displaces picric acid molecule from collagen fibres, which has larger pores and allow larger molecules to enter.

Question 11

what does Van Gieson’s stain differentiate?

Answer 11

muscle from collagen (yellow/red)

Question 12

what is the Masson Trichrome stain used for?

Answer 12

for the detection of collagen fibres in tissues such as skin, heart, etc. on formalin-fixed, paraffin-embedded sections, and may be used for frozen sections as well

Question 13

what colour is collagen in a Masson Trichrome stain?

Answer 13

blue

Question 14

what colour is nuclei in a Masson Trichrome stain?

Answer 14

dark blue/ black

Question 15

what components are stained red in Masson Trichrome stain?

Answer 15

muscle, cytoplasm and keratin

Question 16

what component does Martius Scarlet Blue stain aim to show?

Answer 16

fibrin

Question 17

what are the results for fibrin in Martius Scarlet Blue stain?

Answer 17

early deposits are yellow, mature fibrin is red

Question 18

what is the purpose of silver impregnation?

Answer 18

Impregnation of tissue to enhance the contrast in tissues (not a staining with dye!)

Question 19

what are disadvantages to silver impregnation?

Answer 19

expensive and can be unreliable

Question 20

how is silver located in silver impregnation?

Answer 20

black show fine deposits of silver atoms

Question 21

how does silver impregnation work?

Answer 21

Silver ions (Ag+) reduced to silver atoms (Ag) in reduction reactions at sensitive sites (e.g. aldehyde groups)

Question 22

what are the 3 ways of producing metallic silver in silver impregnation?

Answer 22

1.Argentaffin reaction –argentaffin or enterochromaffin cells of the gut only due to strong reducing pigment.
2.Argyrophil reaction –external reducer needed e.g. formalin (Reticulin fibres, neuroendocrine cells, neurons & axons).
3.Ion-exchange reactions (e.g. phosphates/carbonates of mineralized bone in von Kossa stain).

Question 23

what is reticular tissue?

Answer 23

a special type of connective tissue that predominates in various locations that have a high cellular content.

Question 24

how is reticular tissue arranged?

Answer 24

It has a branched and mesh-like pattern, often called reticulum, due to the arrangement of reticular fibres (reticulin). These fibres are actually type III collagen fibrils.

Question 25

where is reticular tissue located in the body?

Answer 25

Found in e.g. the kidney, liver, the spleen, lymph nodes, Peyer’ patches and bone marrow. Functions as a ‘soft skeleton’

Question 26

what method is usually used to identify reticulin fibres?

Answer 26

silver impregnation method

Question 27

what can the structure of reticulin fibres show?

Answer 27

they reflect function and can show liver fibrosis or cirrhosis and bone marrow fibrosis

Question 28

what colour do reticulin fibres appear in silver impregnation method?

Answer 28

dark brown or dark grey

Question 29

which cells produce reticulin?

Answer 29

reticular cells

Question 30

why do some protocols use neutral red at the end of the reticulin protocol?

Answer 30

it is used as a nuclear counterstain as a last step before dehydration.

Question 31

what is the Von Kossa stain used for?

Answer 31

Von Kossa stain is widely used in histology to detect the presence of abnormal calcium deposits in the body

Question 32

what is the principle of the Von Kossa stain?

Answer 32

Silver impregnation technique. The principle of this coloration is based on the transformation of calcium salts into silver salts: calcium ions, bound to phosphates, are replaced by silver ions brought by a solution of silver nitrate

Question 33

what is amyloid?

Answer 33

an abnormal protein, amino sequences similar or identical to body proteins

Question 34

why are amyloids “bad”?

Answer 34

they form insoluble fibrils that are resistant degradation

Question 35

how are amyloids detected?

Answer 35

with Congo red, polarised light shows green birefringence

Question 36

how are carbohydrates identified?

Answer 36

with PAS stain. Turns pink

Question 37

what is the function of mucus?

Answer 37

Mucus provides physical protection and hydration, excludes pathogens, and is a reservoir for antimicrobial molecules.

Question 38

what is the main component of mucus?

Answer 38

mucin glycoproteins

Question 39

how are goblet cells stained?

Answer 39

AB/PAS. Not H+E

Question 40

what are 2 important lenses in fluorescent microscope

Answer 40

condenser lens, objective lens.

Question 41

how are fluorescent molecules used in a fluorescent microscope?

Answer 41

they’re used to label cellular structure of interest to stand out from the cell.