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97 Cards in this Set
- Front
- Back
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tissue is fixed in order to...
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stop enzymatic action
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Which fixative contains picric acid, formalin and acetic acid?
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Bouin solution
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The volume of fixative should exceed the volume of the tissue by...
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10 to 20 times
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Tissue must be washed in running water after fixation with...
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Zenker solution
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Which fixative contains formalin, potassium dichromate, and mercuric chloride?
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Helly
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Precipitate left in tissues that have been fixed in solutions containing mercuric chloride may be removed by immersion in...
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iodine
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Commercial stock formaldehyde solutions contain what percentage of formaldehyde?
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37%-40%
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Formalin pigment is most likely to form in tissues if the pH of the formalin solution is at or below...
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5.0
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Formalin pigment may be removed from tissue by...
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alcoholic picric acid
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10% formalin is the same as what percentage of formaldehyde?
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4%
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For best results when using formalin as a routine fixative, it must be made...
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neutral
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Absolute alcohol is indicated as a primary fixative if the tissue is to be processed for the demonstration of...
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urate crystals
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Autolysis of tissue is caused by...
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enzymatic activitiy
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To prepare a 10% solution of formalin, how much water should be added to 100mL of stock formaldehyde?
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900mL
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The ratio of stock solution to acid in Zenker fixative is...
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20 parts stock to 1 part acetic acid
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What tissue change will occur if acetic acid is used alone as a fixative?
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swelling
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A good fixative for central nervous system tissue to be stained with silver or gold techniques is...
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formalin ammonium bromide
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After fixing tissue in Bouin solution, the excess picric acid is frequently removed by washing in...
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50% to 70% alcohol
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Carnoy fluid is prepared with acetic acid, alcohol, and...
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chloroform
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The first and most important procedure in the preparation of a tissue for microscopic examination is the choice of...
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fixative
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Fats are usually preserved best if the tissue is fixed in...
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osmium tetroxide
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When alcohol is used as the primary fixative, one should expect...
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excessive tissue shrinkage
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Generally, an increase in the temperature of the fixative solution...
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increases the speed of fixation
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What is a cause of tissue overhardening?
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prolonged fixation
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Fixatives containing chromate salts usually require...
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washing in water
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Substitution of alcohol as the diluting solution for formaldehyde results in...
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better preservation of glycogen
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Zinc salts are added to some formalin fixatives to...
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provide superior nuclear detail
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Tissue fixed in glutaraldehyde is not satisfactory for...why?
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the PAS reaction, the extra aldehyde chain reacts with the schiff's to give a false positive result
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For immunofluorescence, the tissue sould be fixed in...
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nothing, tissue should be unfixed
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What is an example of a nonaqueous combined fixative?
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Carnoy
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What fixatives will leave the tissue protein uncoagulated?
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osmium tetroxide
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To prevent polymerization of formaldehyde, what is added to the commercial stock solutions?
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methyl alcohol
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polymerized formaldehyde is known as...
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paraformaldehyde
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Formaldehyde reacts with protein side chains by combining with the...
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amino group
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Formaldehyde cross-links proteins by reacting with which group?
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NH2 (amino group)
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What is an example of a nonadditive fixative?
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ethyl alcohol
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Potassium dichromate increases availability of what group for binding dyes?
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amino group
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Which types of pigments are preventable?
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formalin and chromium
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Which types of pigments are removable?
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formalin and mercury (chromium is partially removed)
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How is formalin pigment removed?
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saturated alcoholic picric acid, alkaline alcohol
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How is mercury pigment removed?
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iodine followed by sodium thiosulfate
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Can chromium pigment be removed? If so how?
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-partially
-acid alcohol |
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T/F: Formalin fixation stabilizes lipids
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-False
-osmium tetroxide does |
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T/F: Acetic acid is an excellent nuclear fixative
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-True
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T/F: Fat is well preserved by Carnoy solution
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-False
-Osmium Tetroxide |
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T/F: Formalin penetrates rapidly but fixes slowly
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-True
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T/F: 10% formalin is a 1:4 dilution of commercial formalin
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-False
-1:9 dilution |
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T/F: Zenker fixative contains formalin, mercuric chloride, and potassium dichromate
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-False
-mercuric chloride, potassium dichromate, sodium sulfate, acetic acid |
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T/F: Fixation in Helly solution will preserve erythrocytes, while fixation in Zenker solution will not
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-true
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T/F: Bouin solution contains picric acid, formalin and hydrochloric acid
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-false
-picric acid, formalin and acetic acid |
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T/F: Any fixative containing mercuric salts will leave a deposit of crystals in the tissue
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-true
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T/F: Mercury crystals may be removed from tissue by immersion in sodium thiosulfate
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-false
-immersed in iodine and rinsed with sodium thiosulfate |
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T/F: Formalin ammonium bromide is a very good fixative for connective tissue
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-false
-nerve tissue |
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T/F: The fixing fluid considered best for the preservation of nuclear detail is formalin
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-false
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T/F: Formalin pigment can be removed from tissue by immersion in alcoholic picric acid
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-true
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T/F: The volume of the fixative should exced the volume of the tissue by 1 to 2 times
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-false
-10-20 times |
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T/F:Tissue left in fixative beyond the defined time may become excessively hard
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-true
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T/F: Acetic acid is a useful addition to many compound fixatives because of its shrinking action
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-false
-swelling |
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T/F: Since formalin is a coagulant fixative it is considered an excellent fixative for paraffin embedding
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-false
-formalin is noncoagulant |
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T/F: Acetone is sometimes used when a rapid acting fixative is needed
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-true
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T/F: A fixative stops autolysis and putrefaction
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-true
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T/F: If tissues have been fixed in an aqueous fixative, uric acid crystals cannot be demonstrated
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-true
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T/F: A good fixative should penetrate slowly
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-false
-rapidly |
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T/F: If one wishes to prevent the formation of a pigment, formalin solutions must be buffered to a pH above 7.0
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-false
-above 5.0 |
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T/F: Concentrated commercial solutions of formaldehyde are 37%-40% by weight of the gas formaldehyde dissolved in water
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-true
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T/F: Osmium tetroxide chemically fixes lipids
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-true
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T/F: Helly, Zenker, and Orth solutions all contian mercury
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-false
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T/F: Chrome pigment can be prevented by washing the tissues with water following fixation
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-true
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T/F: B-5 fixative contains formalin and potassium
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-false
-formalin, mercuric chloride, sodium acetate |
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T/F: Glutaraldehyde is frequently used to fix specimen for electron microscopy
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-true
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T/F: Orth solution is the best fixative for pheochromocytomas
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-true
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T/F: Heat and desiccation are methods of fixation
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-true
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What is the best fixative for connective tissue?
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-Bouin solution
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What is the best fixative for electron microscopy?
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-osmium tetroxide
-Zamboni solution |
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What is the best fixative for enzymme histochemistry on muscle?
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-frozen section (no fixative)
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What is the best fixative for immunofluorescence?
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-frozen section (no fixative)
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What is the best fixative for pheochromocytomas?
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-Orth solution
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What is the best fixative for phophotungstic acid hematoxylin (PTAH) for cross striations?
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-Zenker solution
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What is the best fixative for urate crystals?
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-absolute alcohol
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What fixative is made up of formaldehyde and mercuric chloride?
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-B-5 fixative
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What fixative is made with acetic acid, Helly solution, and picric acid?
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-Bouin solution
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What fixative is made with absolute alcohol, acetic acid, and chloroform?
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-Carnoy solution
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Which fixative is made with formaldehyde, dibasic sodium phophate and monobasic sodium phosphate?
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-10% neutral buffered formalin
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What fixative consists of 95% alcohol, acetic acid, formaldehyde, and picric acid?
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-Gendre solution
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What fixative contains formaldehyde, mercuric chloride, and potassium dichromate?
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-Helly solution
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Which fixative consists of acetic acid, copper acetate, formaldehyde, and picric acid?
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-Hollande solution
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What fixative is made with formaldehyde and potassium dichromate?
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-Orth solution
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What fixative is made with paraformaldehyde, picric acid, dibasic sodium phosphate, and monobasic sodium phosphate?
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-Zamboni solution
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What fixative contains acetic acid, mercuric chloride and potassium dichromate?
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-Zenker solution
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H and E stained sections fixed in formalin show a brown microcrystalline deposit lying on top of the tissue. This can most likely be prevented in the future by...
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-raising the pH of the formalin above 6.0
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H and E stained sections show a brown microcrystalline deposit lying on top of the tissue. It is especially heavy in bloody areas of the tissue. This pigment can most likely be removed by treating the tissue with...
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-alcoholic picric acid
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H and E stained sections FAIL to reveal uric acid crystals on a case with a clinical diagnosis of gout. One possible explanation for the false-negative result could be that the specimen was fixed in a solution other than...
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-absolute alcohol
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At the time of embedding, a white deposit is noted on tissue fixed in unbuffered zinc formalin and then transferred to phosphate-buffered formalin. One possible explanation could be that the tissue was...
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-transferred to buffered formalin without washing
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Blocked tissue, which had been fixed in Bouin solution, is pulled from the file after being stored for several years. New sections are cut and stained with H and E. No nuclear staining is noted on the new sections, although the original sections stained very well. The most likely explanation is that....
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-picric acid was not remove sufficiently before blocking
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Electron microscopic studies on a section of tumor fixed in 10% neutral-buffered formalin reveal very poor cell preservation. This could be prevented in the future by...
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-fixing some of the tumor in glutaraldehyde solution
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H and E stained sections of liver fixed in a saline solution in the microwave oven show marked distortion of the liver architecture and predominantly pyknotic nuclei. This most likely is the result of...
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-overheating the saline
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H and E stained sections of liver fixed in a saline solution in the microwave oven show marked pyknotic overstained nuclei. This can probably be prevented in the future by ensuring that the temperature is kept below...
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-55 degrees
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