Quiz Flashcards by E E

A yellow solution of decalcifying agent MAY indicate that it contains what?

Nitrous acid

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Used to counteract shrinkage in compound fixatives

Acetic acid

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What inhibits the formation of paraformaldehyde in commercial formalin?

Methanol

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All connective tissues and cells are derived from ____________ cells

mesenchymal

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Used as a post-formalin fixative before trichrome staining

Bouins

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Substrate used with horseradish peroxidase?

Hydrogen peroxide

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Nuclear chromatin is best preserved by which fixatives containing?

Acetic acid

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Reagent used to remove tissue discolouration caused by chromic acid (Grocott)

Sodium bisulphite

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Fixative that forms black granular deposits in tissues

Mercurial fixatives

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In a dye molecule, the hydroxyl group is a/an?

Auxochrome

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3 main components of Bouin’s

picric acid
acetic acid
formalin

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Fixative that would LEAST likely affect IHC staining

Alcohol

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Streaming artifact occurs with ___________

glycogen

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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

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A solution which contains positive and negative dye ions is called a _______ dye

neutral

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How to remove paraformaldehyde precipitate in concentrated formaldehyde?

Filtering

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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

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Max length of time tissue can be oxidized w/ periodic acid

No maximum - you cannot over-oxidize with periodic acid (unlike chromic acid)

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Prolonged exposure of tissue to xylene during paraffin processing causes?

Excessive hardening of tissue

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Dense IRREGULAR connective tissue may be found in

1) tendon
2) ligament
3) dermis
4) bone

3) dermis

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Why is it important to cut Congo Red sections at 6-10 microns?

Required to give proper birefringence

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Effect of formalin on neutral fats?

Nothing - leaves them unaltered

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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

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___________ are responsible for myelination of axons in the CNS

Oligodendrocytes

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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

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?

1. 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