Wheatley Trichrome Staining 50 FAQs and 30 MCQs:
Wheatley Trichrome Staining 50 FAQs:
What is the Wheatley Trichrome staining technique used for?
It is used for the detection and identification of intestinal protozoans from stool samples.
Who developed the original Trichrome stain?
Gomori developed the original Trichrome stain in 1951.
What modifications did Wheatley make to Gomori’s technique?
Wheatley added fixation and hydration steps to create a rapid and simple staining procedure.
What types of protozoan morphologies can be identified using this stain?
Cysts and trophozoites can be identified.
What is the principle of Wheatley Trichrome Stain?
It uses dyes to stain nuclear chromatin, chromatoid bodies, and cytoplasm, providing contrast for identifying protozoa.
What are the main components of the Trichrome stain solution?
Chromotrope 2R, Light Green SF, Phosphotungstic acid, Glacial acetic acid, and distilled water.
What is the shelf life of the Trichrome stain solution?
The shelf life is 24 months when stored properly.
What type of stool samples are used for this stain?
What type of stool samples are used for this stain?
What is the purpose of iodine-alcohol in the staining process?
It removes mercuric chloride from Schaudinn’s or PVA fixatives.
What is the role of acid ethanol in the procedure?
It acts as a decolorizing agent to differentiate structures.
What magnification is required to examine the stained smear?
The smear is examined under oil immersion at 200-300 fields.
What are the staining characteristics of protozoan trophozoites?
The cytoplasm stains blue-green or light purple, and nuclei stain red.
What are the limitations of Wheatley Trichrome Stain?
It cannot stain helminth eggs, larvae, or certain protozoa like Cryptosporidium parvum.
What are the applications of Wheatley Trichrome Stain?
It is used for diagnosing intestinal protozoa infections and identifying parasitic morphologies.
Why is it important to use gloves during the staining procedure?
To avoid contamination and exposure to hazardous chemicals.
How is a fresh stool sample prepared for staining?
Small samples are smeared thinly on a slide and fixed in Schaudinn’s fixative.
What is the purpose of PVA in stool sample preparation?
PVA preserves the stool sample and helps it adhere to the slide.
How long should a PVA-fixed smear dry before staining?
It should dry for several hours at 35-37°C or overnight at room temperature.
What is the purpose of the iodine-alcohol step?
It removes mercuric chloride from the fixative.
How long should slides remain in Trichrome stain?
Slides should remain in the stain for 10 minutes.
What is the purpose of the xylene step in the procedure?
Xylene clears the slide and prepares it for mounting.
What mounting medium is used for the stained smear?
Permount or a similar mounting medium is used.
How long should the smear dry after mounting?
It should dry overnight or for at least 1 hour at 37°C.
What is the purpose of the acid ethanol step?
It differentiates the stain by removing excess color.
Why is it important to drain slides between solutions?
To prevent carryover of solutions, which can affect staining quality.
What color do protozoan cysts stain?
Cysts appear more purple.
What color do human cells like RBCs and PMNs stain?
They stain red.
What color does the background stain?
The background stains green.
What happens to glycogen molecules during staining?
They dissolve and appear as clear areas in the organism.
What does it mean if the smear is predominantly green?
It may indicate inadequate removal of iodine.
What does it mean if the smear is too red?
It may indicate improper fixation or over-decolorization.
What are the typical staining reactions of nuclear chromatin?
Nuclear chromatin stains red to purple-red.
What are the typical staining reactions of cytoplasm?
Cytoplasm stains blue-green with a faint purple tinge.
What are the typical staining reactions of yeast cells?
Yeast cells vary in staining reactions but often stain red.
What are the typical staining reactions of bacteria?
Bacteria stain red to purple-red.
Why can’t helminth eggs and larvae be stained with Trichrome?
The stain is not designed for their permanent staining.
Why are some protozoans like Cryptosporidium difficult to identify?
Cryptosporidium’s small size (4–6 µm) and weak stain uptake due to their resistant oocyst wall result in poor contrast with Wheatley Trichrome, making them hard to detect compared to acid-fast methods.
What causes dark crystalline materials on the smear?
Saturation of the iodine-alcohol solution or insufficient time in the solution.
What causes a smear to peel or wash off during staining?
Inadequate drying of the smear before staining.
What causes a smear to appear cloudy?
Carryover of solutions or incomplete dehydration.
What causes a lack of contrast in the smear?
Prolonged destaining in acid ethanol or carryover of solutions.
What should be done if the smear is too green?
Lengthen the timing of iodine removal steps or change ethanol solutions more frequently.
What should be done if the smear is too red?
Ensure proper fixation and avoid over-decolorization.
What should be done if the smear is cloudy?
Change solutions regularly and ensure proper dehydration.
What should be done if the smear lacks contrast?
Observe the smear carefully during decolorization and avoid prolonged acid ethanol exposure.
What precautions should be taken when handling Trichrome stain?
Wear gloves, avoid inhalation, and follow safety guidelines.
How should Trichrome stain be stored?
Store in a glass or plastic bottle at room temperature, protected from light.
What is the shelf life of the stain?
The shelf life is 24 months.
What should be done if the stain changes color?
Discard the stain if it changes from dark-blue to purple.
What should be done with contaminated materials after staining?
Properly sterilize specimens, containers, and test materials after use.
Wheatley Trichrome Staining 30 MCQs:
- What is the primary purpose of the Wheatley Trichrome Stain?
a) Staining bacterial cells
b) Detecting intestinal protozoans
c) Identifying fungal spores
d) Staining helminth eggs - Who originally developed the Trichrome stain?
a) Wheatley
b) Gomori
c) Ziehl
d) Neelsen - What modification did Wheatley make to Gomori’s Trichrome stain?
a) Added iodine-alcohol step
b) Added fixation and hydration steps
c) Reduced staining time to 1 minute
d) Eliminated the use of xylene - Which of the following is NOT a component of the Trichrome stain solution?
a) Chromotrope 2R
b) Light Green SF
c) Phosphotungstic acid
d) Methylene blue - What type of stool sample is used for Wheatley Trichrome staining?
a) Fresh or PVA-fixed
b) Frozen stool
c) Urine-contaminated stool
d) Formalin-preserved only - What is the purpose of iodine-alcohol in the staining process?
a) To stain the cytoplasm
b) To remove mercuric chloride
c) To decolorize the smear
d) To fix the stool sample - How long should slides remain in Trichrome stain?
a) 1 minute
b) 5 minutes
c) 10 minutes
d) 30 minutes - What is the purpose of acid ethanol in the staining process?
a) To fix the smear
b) To decolorize the smear
c) To stain the nuclei
d) To remove iodine - What magnification is used to examine the stained smear?
a) 40x
b) 100x (oil immersion)
c) 400x
d) 1000x - What color do protozoan trophozoites stain?
a) Blue-green or light purple
b) Red
c) Green
d) Yellow - What color do human cells like RBCs and PMNs stain?
a) Red
b) Green
c) Blue
d) Purple - What color does the background stain in a Wheatley Trichrome smear?
a) Green
b) Red
c) Blue
d) Purple - Which of the following cannot be stained by Wheatley Trichrome Stain?
a) Intestinal protozoan cysts
b) Helminth eggs
c) Yeast cells
d) Human cells - What is the shelf life of the Trichrome stain solution?
a) 6 months
b) 12 months
c) 24 months
d) 36 months - What is the purpose of xylene in the staining process?
a) To fix the smear
b) To clear the slide
c) To stain the nuclei
d) To decolorize the smear - What happens to glycogen molecules during staining?
a) They stain red
b) They dissolve and appear clear
c) They stain green
d) They stain purple - What is the primary limitation of Wheatley Trichrome Stain?
a) It cannot stain protozoans
b) It cannot stain helminth eggs and larvae
c) It cannot stain human cells
d) It cannot stain yeast cells - Which protozoan is difficult to identify using Wheatley Trichrome Stain?
a) Entamoeba histolytica
b) Cryptosporidium parvum
c) Giardia lamblia
d) Trichomonas vaginalis - What is the purpose of the mounting medium in the staining process?
a) To fix the smear
b) To decolorize the smear
c) To preserve the stained smear
d) To remove iodine - What is the recommended drying time for a mounted smear?
a) 1 hour at 37°C
b) 2 hours at room temperature
c) Overnight at room temperature
d) Both a and c - What causes dark crystalline materials on the smear?
a) Over-staining
b) Saturation of iodine-alcohol solution
c) Inadequate drying
d) Over-decolorization - What is the purpose of the iodine step in the staining process?
a) To stain the nuclei
b) To remove mercuric chloride
c) To decolorize the smear
d) To fix the stool sample - What is the recommended fixative for stool samples in Wheatley Trichrome staining?
a) Formalin
b) PVA or Schaudinn’s fixative
c) Ethanol
d) Xylene - What is the purpose of the acid ethanol step?
a) To differentiate the stain
b) To fix the smear
c) To stain the nuclei
d) To remove iodine - What is the primary application of Wheatley Trichrome Stain?
a) Staining bacterial cells
b) Diagnosing intestinal protozoa infections
c) Identifying fungal spores
d) Staining helminth eggs - What is the recommended storage condition for Trichrome stain?
a) Refrigerated at 4°C
b) Frozen at -20°C
c) Room temperature, protected from light
d) Heated at 37°C - What is the purpose of the ethanol rinse after decolorization?
a) To halt decolorization
b) To fix the smear
c) To stain the nuclei
d) To remove iodine - What is the primary reason for using PVA in stool sample preparation?
a) To preserve the stool sample
b) To decolorize the smear
c) To stain the nuclei
d) To remove iodine - What is the primary limitation of Wheatley Trichrome Stain for Cryptosporidium?
a) It cannot stain Cryptosporidium
b) It requires acid-fast staining for Cryptosporidium
c) It over-stains Cryptosporidium
d) It cannot differentiate Cryptosporidium from yeast - What is the primary purpose of the xylene step in the staining process?
a) To clear the slide
b) To fix the smear
c) To stain the nuclei
d) To decolorize the smear
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