Histology Certification Staining Methods 5 — Questions and Answers
Question 1: Which staining technique is used to demonstrate Helicobacter pylori in gastric biopsy sections?
- PAS stain
- Giemsa or Warthin-Starry stain (Correct answer)
- Ziehl-Neelsen stain
- Mucicarmine stain
Correct answer: Giemsa or Warthin-Starry stain
Giemsa and Warthin-Starry silver stain are both commonly used to highlight H. pylori organisms in gastric mucosa.
Question 2: What is the mechanism by which eosin stains cytoplasmic components in H&E?
- Ionic attraction between the anionic dye and cationic cytoplasmic proteins (Correct answer)
- Covalent bonding to amino acid side chains
- Hydrophobic partitioning into lipid membranes
- Chelation of metal ions in proteins
Correct answer: Ionic attraction between the anionic dye and cationic cytoplasmic proteins
Eosin is an anionic (acidic) dye that binds electrostatically to positively charged (basic) cytoplasmic proteins and other cationic tissue components.
Question 3: Mucicarmine stain specifically highlights which organism in tissue sections?
- Aspergillus species
- Cryptococcus neoformans (Correct answer)
- Candida albicans
- Histoplasma capsulatum
Correct answer: Cryptococcus neoformans
Mucicarmine stains the thick polysaccharide capsule of Cryptococcus neoformans bright rose-red, making it a useful diagnostic stain.
Question 4: The Bielschowsky silver stain is primarily used in which pathological condition?
- Liver fibrosis
- Neuritic plaques and neurofibrillary tangles in Alzheimer's disease (Correct answer)
- Renal amyloidosis
- Pulmonary fibrosis
Correct answer: Neuritic plaques and neurofibrillary tangles in Alzheimer's disease
Bielschowsky is an argentaffin silver stain used in neuropathology to demonstrate axons, neuritic plaques, and neurofibrillary tangles associated with Alzheimer's disease.
Question 5: What is 'background staining' and how is it typically reduced in immunohistochemistry?
- Staining of nuclei; reduced by omitting hematoxylin
- Nonspecific antibody binding to tissue; reduced by blocking with serum or BSA (Correct answer)
- Overstaining with DAB; reduced by shortening incubation
- Tissue autofluorescence; reduced by using aldehyde fixatives
Correct answer: Nonspecific antibody binding to tissue; reduced by blocking with serum or BSA
Background staining results from nonspecific antibody binding and is minimized by pre-incubating tissue with normal serum, BSA, or commercial blocking reagents.
Question 6: Which stain is used to identify mast cells based on metachromatic staining of their granules?
- Toluidine blue
- Alcian blue at pH 1.0
- Both toluidine blue and Alcian blue at pH 1.0 (Correct answer)
- Congo red
Correct answer: Both toluidine blue and Alcian blue at pH 1.0
Both toluidine blue (producing metachromatic purple-red granules) and Alcian blue at pH 1.0 (staining only highly sulfated proteoglycans) are used to identify mast cell granules.
Question 7: In fluorescence in situ hybridization (FISH), what is the primary purpose of the probe?
- To permeabilize the nuclear membrane for antibody access
- To hybridize to a specific complementary DNA or RNA sequence in the tissue (Correct answer)
- To amplify protein expression signals
- To fix chromosomes to the slide surface
Correct answer: To hybridize to a specific complementary DNA or RNA sequence in the tissue
FISH probes are fluorochrome-labeled nucleic acid sequences that hybridize to complementary target sequences, allowing visualization of specific chromosomal loci or gene copy numbers.
Histology Certification Staining Methods 5
Which staining technique is used to demonstrate Helicobacter pylori in gastric biopsy sections?