Practice quizzes Flashcards
Advantage of using mercuric chloride in a fixative solution?
It doesn’t block amino groups that bind anionic dyes
What should be used to neutralize a strong acid spill?
Buffer that would bring pH to neutral
NOT a strong base
Purpose of sodium thiosulphate in silver impregnation methods?
Remove unreduced silver salts
A tissue has sulfated proteoglycans, collagen type II, no elastic fibres, and has no direct blood supply. This tissue is:
Hyaline cartilage
Which tissue would you expect to have considerable background peroxidase activity that may interfere with immunoperoxidase staining?
Bone marrow
Immunoperoxidase reagent that is a suspected carcinogen
DAB
The Weigert - Van Gieson stain for connective tissue gives what results?
Nuclei: ?
Collagen: ?
Muscle and cytoplasm: ?
Nuclei - blue/black
Collagen - red
Muscle/cytoplasm - yellow
This fixative ingredient serves to precipitate nucleic acids:
Acetic acid
If the alcian blue pH 2.5/PAS method sequence were reversed (ie. PAS was done before the alcian blue), then what would happen?
All PAS-positive sites would also bind to the Alcian blue stain
A colourless solution prepared by disrupting the chromophore of pararosaniline
Schiff’s reagent
What type of microscopy?
Excitation occurs at higher energy wavelengths and emission is seen at lower energy wavelengths
Fluorescence microscopy
If you wished to detect ferrous iron in tissue you could use which of the following as a detection reagent?
Potassium ferricyanide
Which of the following is an anionic auxochrome?
1) sulfonic acid groups
2) nitro groups
3) amino groups
4) bromine groups
1) sulfonic acid groups
Which of the following statements is true?
1) large volumes of alcohols and xylene are suitably stored on the laboratory bench top.
2) it is safe to store concentrated HCL next to concentrated perchloric acid in a flammables cabinet.
3) xylene and glacial acetic acid should be stored in separate cabinets.
4) xylene and alcohol should be stored in separate cabinets
3) xylene and glacial acetic acid should be stored in separate cabinets.
Nucleic acids and carbohydrates may be hydrolyzed by prolonged fixation in: ?
Bouin’s
Immunohistochemical detection of tissue antigens using the biotin-strepatavidin system utilizes:
1) primary antibody, enzyme-labelled secondary antibody, peroxidase
2) primary antibody, biotinylated secondary antibody, peroxidase
3) primary antibody, biotinylated secondary antibody, strepatavidin-peroxidase
4) primary antibody, secondary antibody, strepatavidin-peroxidase
3) primary antibody, biotinylated secondary antibody, strepatavidin-peroxidase
What stain can detect proteoglycan deposition in cardiac biopsies?
Alcian blue, pH 2.5
When is decalcification of calcified tissue ALWAYS done?
After fixation
How to fix a Wright-Giemsa stained slide where RBCs are too pink, nuclei are pale violet, eosinophil granules are bright orange-red?
Adjust the pH of the staining buffer to a HIGHER pH level
What is a suitable chemical test of Schiff’s reagent potency?
React some of it w/ formaldehyde
Why is post-fixation in Bouin’s or Zenker’s before Trichrome procedures necessary?
They counteract the effects of formalin crosslinking
Which of the following would be the best positive control for cytokeratin staining?
1) lymph node follicles
2) muscle
3) astrocytes
4) simple columnar epithelium
4) simple columnar epithelium
Decontamination of a cryostat following a lung specimen containing acid-fast bacilli may be achieved by:
1) alcohol swabbing
2) using a phenolic compound followed by alcohol swabbing
3) using bleach
4) using ethylene oxide
2) using a phenolic compound followed by alcohol swabbing
What would cause tissue to stain magenta w/ Schiff’s reagent without prior oxidation w/ periodic acid?
It had pre-formed aldehydes
Which of the following is true?
1) formalin-fixed tissues are a biohazard
2) formalin fixed tissues are a physical hazard
3) formalin-fixed tissues are potentially carcinogenic
4) formalin-fixed tissues are not hazardous
3) formalin-fixed tissues are potentially carcinogenic
Which of the following fixation methods would least affect antigen functional groups?
1) formalin fixation for 24 hrs
2) Bouin’s fixation for 6 hrs
3) alcohol fixation for 2 hrs
4) Formalin fixation for 6 hrs
3) alcohol fixation for 2 hrs
Function of ferric ammonium sulfate in Gordon & Sweet’s method for reticulin?
Sensitizing agent
Best way to detect the end-point of decal?
X-ray
Which fixative could cause a false positive reaction with Schiff’s reagent?
Glutaraldehdye
This fixative produces noxious/irritating gases if heated
Formalin
Which of the following may be placed in a bench top oven at 60?C?
1) formaldehyde solutions
2) saturated mercuric chloride solutions
3) glacial acetic acid
4) acetone
2) saturated mercuric chloride solutions
Why is sodium iodate incorporated into Gill’s hematoxylin?
To oxidize the hematoxylin to hematein
What is responsible for the limited life span in iron hematoxylin?
Over-oxidation of hematein to oxyhematein
What is the reason for lowering the pH of anionic stain solutions?
To protonate amino groups in tissue
Which reagent would have a short shelf life at room temperature?
1) 1M HCl
2) Schiff’s Reagent
3) 3% sulfuric acid
4) sterile saline
2) Schiff’s Reagent
What do cationic dyes stain at pH 1.0?
Sulfated sugars
Purpose of chromic acid in Grocott’s methenamine silver method?
Oxidize carbohydrates in the fungal cell coat
Why can’t lipid staining be performed on paraffin sections?
Lipids are extracted in alcohol and xylene steps
What type of auxochromes do cationic dyes have?
Amino groups
Light source for epifluorescence microscopy?
Xenon lamp
What does a germinal centre indicate?
Lymphoid proliferation
In which cells are Crystals of Reinke found in?
Leydig cells
