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94 Cards in this Set
- Front
- Back
Which fixative contains picric acid, formalin, and acetic acid?
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Bouins
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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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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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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%-70% ETOH
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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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Which fixative will leave the 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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Potassium dichromate increases availability of which group for binding?
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NH2
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Acetic acid is an excellent fixative:
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TRUE
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Formalin penetrates rapidly but fixes slowy:
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TRUE
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10% formalin is a 1:4 dilution of commercial formalin
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FALSE
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Zenker fixative contains formalin, mercuric choride, and potassium dichromate
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FALSE
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Bouin solution contains picric acid, formalin, and hydrochloric acid
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FALSE
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Mercury crystals may be reoved from tissue by immersion in sodium thiosulfate.
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FALSE
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Formalin ammonium bromide is a very good fixative for connective tissue.
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FALSE
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B-5 fixative contains formalin and potassium dichromate.
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FALSE
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Gluteraldehyde is frequently used to fix specimens for electron microscopy.
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TRUE
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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&E. No nuclear staing is noted on the new sections, although the original sections stained very well.
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Picric acid was not removed 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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Tissue must be washed in running water after fixation in
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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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Commercial stock formaldehyde solutions contain
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37%-40% formaldehyde
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Is Carnoy fixative nonaqueous
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Yes
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Fat is well perserved by Carnoy solution
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FALSE
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Formalin ammonium bromide is a very good fixative for connective tissue
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FALSE
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Helly, Zenker, and Orth all contain mercury
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FALSE
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B-5 Fixative contains formalin and potassium dichromate
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FALSE
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What is a dehydrating agent?
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alcohol
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What is a dehydrating agent?
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alcohol
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A clearing agent for use in processing tissues for paraffin embedding must be miscible with the:
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dehydrant and parrafin
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Dioxane is a reagent that can be used:
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for both dehydrating and clearing tissues
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A reagent that CANNOT be used for dehydrating tissue is:
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benzene
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Most commonly,the paraffin used for embedding tissues is kept at approximately:
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60 C
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A disadvantage of the use of dioxane in processing tissues is that it is:
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toxic
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The chief objection to the use of xylene as a clearing agent for processing tisssues is that xylene is:
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likely to harden tissue
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A good paraffin for routine use is one with a melting point of:
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55 C to 58 C
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Which of the following chemicals is NOT a clearing agent?
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ethanol
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Overheating of the parraffin used to embed may cause:
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cracking of the block
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One advantage of the paraffin technique is that:
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serial sections are easy to obtain
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When cutting paraffin embedded tissues, if the tissue seems hard and brittle, one source of trouble is likely to be:
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overheated paraffin
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The process of removing water from tissue is called:
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dehydration
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Reagents that both clear and dehydrate are called:
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universal solvents
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Paraffin that is considered soft:
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is most useful when thick sections are desired
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When used for clearing, cedar wood oil must be followed by:
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xylene
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Paraffin is cooled as rapidly as possible after embedding tissue in order to:
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prevent the formation of large crystals
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The dehydration and clearing steps can be omitted when using:
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water-soluble wax
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Specimens for electron microscopy are embedded in glycol methacrylate.
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False
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Sections processed by the celloidin method show less shrinkage than when processed by the paraffin technique.
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True
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The most appropriate method of processing tissue for most enzyme demonstration is frozen sections.
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True
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Overheating of the paraffin used for infiltration causes shrinkage and overhardening of the tissue.
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True
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Skin sections ar embedded so that the epithelial surface is faced down in the block.
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False
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Ion exchange resin and electrolytic methods of decalcification fall under the broad heading of acid methods.
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True
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When undecalcifed bone is to be sectioned, it must be embedded in Carbowax.
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False
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Heating the solution is a good method of increasing the rate of decalcification.
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False
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Tissue will contain ice crystal artifacts when frozen slowly.
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True
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Tissues are usually infiltrated with paraffin directly from an essential oil.
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False
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A chelating agent exchanges another ion for the calcium ion.
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False
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Carbowax is a blend of liquid polyethylene glycol and wax.
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True
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One result of incomplete clearing is poor infiltration with Carbowax.
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False
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Bone sections should be embedded parallel to the long axis of the block.
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False
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If phosphate-buffered formalin fixation is followed by dehydration beginning with 80% alcohol, phosphates may be precipitated.
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True
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The best method of checking Zenker-fixed tissue for the completeness of decalcification is radio-logic examination.
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False
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Xylene and toluene are aromatic hydrocarbons.
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True
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One cause of uneven staining with H&E may be water contamination of the clearing agent on the processor.
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True
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During microtomy,it is noted that most of the tissue is very hard and shrunken. One of the first things to check to prevent its happening in the future is the:
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temperature of the infiltrating paraffin
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H&E-stained sections show very uneven staining of the tissue, with poor nuclear detail. One possible cause is:
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water in the clearing agent
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Phosphate-buffered formaldehyde is used in the first two stations of the closed processor. A white precipitate is forming in the processor tubing, and the tissue is more difficult to cut than usual. One of the first things to check to correct the problem is the:
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percent alcohol used as the first dehydrant
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At microtomy,formalin-fixed, paraffin-embedded kidney sections are soft and mushy. This is most likely due to:
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inadequate dehydration and clearing
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Aqueous unbuffered zinc formalin is used at the first stage on the closed processor, followed by phosphate-buffered formalin and 65% alcohol. It is noted that a white precipitate is forming on the processor tubing. This precipitate is most likely due to:
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the formation of zinc phosphate
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Many of the zinc formalin-fixed biopsy specimans are hard and brittle and show microscopic chatter. This will result if the specimans are:
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processed incorrectly
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The ability of the microscope to separate small details is defined as:
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resolution
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Sections 90-nm thick are commonly cut with a/an:
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ultramicrotome
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Tissues embedded in glycol methacrylate are commonly cut with a/an:
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rotary microtome
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The regular laboratory incubator maintains a temperature of about:
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37 C
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When the magnification can be changed without the need to refocus, the microscope objectives are said to be:
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parfocal
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If a ribbon splits when cutting paraffin sections, the trouble is most likely due to:
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nicks in the knife
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The bevel angle of most American manufactured knives is:
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28-32 degrees
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The temperature of the oven used to maintain a supply of melted paraffin for embedding tissue should be about:
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60 C
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Doubly refractile particles are examined using:
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polarized light
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Crooked paraffin ribbons may be caused by
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nonparallel block horizontal edges
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When using a microscope with x10 ocular and a x40 objective, the total magnification is approximately:
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400
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The clearance angle of the microtome knife should be:
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3 to 8
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The ordinary refrigerator, when operating normally, has a temperature that approaches:
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4 C
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When a lens for a light microscope has been corrected for two colors, it is said to be :
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achromatic
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When using paraffin with a melting point of 55 C to 57 C, the most common temperature for floating sections on a flotation bath is approximately:
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45 C to 50 C
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Compressed or wrinkled sections may be caused by:
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too little knife tilt
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The scanning objective on the light microscope is found:
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at the lower end of the body tube
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Various sized holes are noted in sections of paraffin-embedded liver on the flotation bath. With further ribboning, these holes decrease in size and disappear. The most likely cause of the holes is :
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facing the block too aggressively
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Birefringent substances are best examined with which of the following microscopes?
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polarizing
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During microtomy, the sections lift from the knife as the block is raised. The most likely cause is:
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a dull knife
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Microscopic examination of an H&E-stained section reveals marked chatter, especially at the edges of the tissue. This was most likely caused by:
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overdehydration of the tissue
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During cryotomy, sections of varying thickness are obtained. This can most likely be corrected by:
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increasing the knife tilt
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When checking the pH of a staining solution,the pH meter should be calibrated using a standard solution with a pH value:
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closest to that of the staining solution
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