Quiz Flashcards
A yellow solution of decalcifying agent MAY indicate that it contains what?
Nitrous acid
Used to counteract shrinkage in compound fixatives
Acetic acid
What inhibits the formation of paraformaldehyde in commercial formalin?
Methanol
All connective tissues and cells are derived from ____________ cells
mesenchymal
Used as a post-formalin fixative before trichrome staining
Bouins
Substrate used with horseradish peroxidase?
Hydrogen peroxide
Nuclear chromatin is best preserved by which fixatives containing?
Acetic acid
Reagent used to remove tissue discolouration caused by chromic acid (Grocott)
Sodium bisulphite
Fixative that forms black granular deposits in tissues
Mercurial fixatives
In a dye molecule, the hydroxyl group is a/an?
Auxochrome
3 main components of Bouin’s
- picric acid
- acetic acid
- formalin
Fixative that would LEAST likely affect IHC staining
Alcohol
Streaming artifact occurs with ___________
glycogen
Eosin would most likely be quickly differentiated by.
1) treating with acid
2) raising the pH of the rinse solution
3) treating with xylene
4) washing in running water
2) raising the pH of the rinse solution
A solution which contains positive and negative dye ions is called a _______ dye
neutral
How to remove paraformaldehyde precipitate in concentrated formaldehyde?
Filtering
What is added to Zenker’s fixative stock just before use?
a. HCl
b. 10% formalin
c. picric acid
d. glacial acetic acid
d. glacial acetic acid
Max length of time tissue can be oxidized w/ periodic acid
No maximum - you cannot over-oxidize with periodic acid (unlike chromic acid)
Prolonged exposure of tissue to xylene during paraffin processing causes?
Excessive hardening of tissue
Dense IRREGULAR connective tissue may be found in
1) tendon
2) ligament
3) dermis
4) bone
3) dermis
Why is it important to cut Congo Red sections at 6-10 microns?
Required to give proper birefringence
Effect of formalin on neutral fats?
Nothing - leaves them unaltered
Which of the following are not phagocytic cells?
a) Kupffer cells
b) macrophages
c) histiocytes
d) Langerhans giant cells
e) mast cells
e) mast cells
___________ are responsible for myelination of axons in the CNS
Oligodendrocytes
If you find that your muscle staining is gray-pink instead of red in your trichrome procedure
1) left the fast green on for too long
2) did not treat the sections long enough in Bouin’s fixative @60°C
3) forgot the phosphomolybdic acid step
4) iron hematoxylin was over-differentiated by ferric chloride
2) did not treat the sections long enough in Bouin’s fixative @60°C
What causes formalin pigment to form?
Acid pH in formalin
The purpose for incorporating acetic acid in hematoxylin solutions is to
1) fix or precipitate nucleic acids
2) suppress ionization of negative charges in background tissues
3) prevent growth of microorganisms in the solution
4) oxidize the staining solution
2) suppress ionization of negative charges in background tissues
Cytoplasmic dye in Van Gieson’s
Picric acid
Picric acid may be removed from tissue sections by.
1) rinsing with a slightly alkaline buffer or salt solution
2) rinsing in a weak acid solution
3) rinsing in formaldehyde
4) none of the above
1) rinsing with a slightly alkaline buffer or salt solution
Mercury fixative pigments are removed by treatment with?
Alcoholic iodine followed by sodium thiosulphate
This fixative fixes by forming methylene bridges
Formaldehyde
3 reasons a PASD stain is lighter pink than usual
- Tissue under-oxidized (leave in periodic acid longer)
- Schiff’s reagent expired
- Insufficient washing after Schiff’s (wash longer + in warm water to intensify pink)
Decolourizer in ZN method?
Acid/alcohol
The most rapid removal of eosin from tissue sites in over-stained sections would be
1) rinsing in 95% ethanol
2) rinsing in water
3) rinsing in absolute ethanol
4) rinsing in 2% w/v sodium bicarbonate
4) rinsing in 2% w/v sodium bicarbonate
Why is non-buffered formalin required in reticulin stain?
In order to reduce the silver, the tissue requires a more ACIDIC reducing agent
PAS reaction is dependent on the production of ___________ groups
aldehyde
Purpose of secondary fixation?
To enhance the staining of tissue
The purpose of incorporating acetic acid in hematoxylin solutions is to?
fix or precipitate nucleic acids
b) ensure selective ionization of nucleic acids
c) prevent growth of microorganisms in the solution
d) oxidize the staining solution
b) ensure selective ionization of nucleic acids
If you find that your collagen is purple upon completion of your trichrome stain?
1) you have forgotten the phosphomolybdic acid step in your procedure
2) you have left the Ponceau fuchsin on too long
3) you have left the fast green on for too short a time
4) you have rinsed in water instead of 1% acetic acid
1) you have forgotten the phosphomolybdic acid step in your procedure
Which component in Zenker’s requires washing the tissue well under running water?
Potassium dichromate
100% formalin is what %formaldehyde?
40%
Reagent used to remove tissue discolouration caused by potassium permanganate (retic)
Oxalic acid
A pigment bleached by the use of alcoholic picric acid?
Formalin
*Seen as brown-black crystalline deposits in bloody areas
Fixative used for bone marrows
B5
Purpose of adding HCl to Weigert hematoxylin
Lower pH which prevents background non-specific staining
Hematein-iron bond from dissociates in alkaline solution
___________ are responsible for myelination of axonis in the PNS
Schwann cells
Which of the following decalcifying agents can produce a toxic gas when in contact whith formalin.
a) EDTA
b) HCl
c) Nitric acid
d) Formic acid
b) HCl
Tissue control for Alcian Blue pH 1.0? 2.5?
- 0 - umbilical cord
2. 5 - small bowel
Which of the following fixation methods would least affect antigen functional groups.
a) formalin fixation
b) Bouin’s fixation
c) alcohol fixation
d) snap freezing
d) snap freezing
Why are frozen sections employed in muscle histochemistry?
a) muscle enzymes are still viable after freezing
b) muscle tissue is damaged by formalin
c) tradition
d) formalin fixation damages muscle nuclei
a) muscle enzymes are still viable after freezing
Endogenous peroxidase is quenched by the addition of which of the following
a) Biotin
b) Buffer
c) 1:1 mixture of hydrogen peroxide and methanol
d) an excess of Horse radish peroxidase
c) 1:1 mixture of hydrogen peroxide and methanol
Used in trichrome stain to remove red staining from collagen
Phosphomolybdic or phosphotungstic acid
Preferred fixative for electron microscopy?
Glutaraldehyde
Why can’t lipid staining be performed on paraffin sections?
The lipids are extracted during alcohol and xylene steps
Why is charged slide required for a retic stain?
Silver solution very alkaline - can wash tissue off slide (occurs w/ very acidic/alkaline solutions)
What are formed aldehydes converted to if a tissue is over-oxidized?
Converted to ketones
A coloured compound without an auxochrome
Lysochrome
White pulp of spleen is mostly composed of?
Lymphocytes
What is the solution that differentiates the cytoplasmic stain from collage in trichrome procedure?
Phosphomolybdic acid
Quenching = quickly freezing tissue to _______ degC
-160 degC
Reducing agent in Von Kossa
Light
In the PAP method
a) the link antibody is from the same species as the primary antibody
b) the link antibody is directed against peroxidase
c) the link antibody is from a different species as the primary antibody
d) the link antibody is conjugated with peroxidase
c) the link antibody is from a different species as the primary antibody.
What should tissue be fixed in if urate crystals are to be demonstrated?
Ethanol
Which fixative doesn’t coagulate/precipitate protein?
a. mercuric chloride
b. ethyl alcohol
c. picric acid
d. formaldehyde
e. chromic acid
d. formaldehyde
Preferred fixative for electron microscopy
Glutaraldehyde
A substance that can be classified as argentaffin
melanin
The component in Zenker’s fluid that requires washing the tissue well in running water is?
Potassium dichromate
Cause of ZN-stained tissue to be too pink?
Under-differentiation or improper acid/alcohol concentration
Chemical used to remove plastic coverslip? Glass?
Plastic - acetone
Glass - xylene
A quinoid ring structure in a dye molecule is a/an?
Chromophore
Everything but muscle stained properly after Alcian blue/Van Gieson stain - probable cause?
Yellow picrates washed out after Van Gieson - slides should be dehydrated immediately
What is the function of HCl in Perl’s Prussian Blue?
Separates the iron from its transport protein (b/c it demonstrates ferric iron)
What should tissue be fixed in to demonstrate urate crystals?
Ethanol
Mechanism of action behind antigen retrieval?
Hydrolysis of methylene bridges
Stain for ferrous (Fe2+) iron?
Turnbull’s blue
