ASCP Special Stains and Histochemistry 2 — Questions and Answers
Question 1: The Alcian blue stain at pH 2.5 is used to identify what type of tissue component?
- Neutral mucins
- Acid mucopolysaccharides (acid mucins) (Correct answer)
- Glycogen
- Elastic fibers
Correct answer: Acid mucopolysaccharides (acid mucins)
Alcian blue at pH 2.5 stains both sulfated and carboxylated (acid) mucopolysaccharides blue, distinguishing them from neutral mucins.
Question 2: In the Gram stain used in histology (Brown and Brenn technique), how do gram-positive bacteria appear?
- Red/pink
- Blue-black (Correct answer)
- Yellow
- Green
Correct answer: Blue-black
Gram-positive bacteria retain the crystal violet-iodine complex after decolorization and appear blue-black in the Brown and Brenn tissue Gram stain.
Question 3: Which special stain is used to highlight elastic fibers in tissue sections?
- Verhoeff's iron hematoxylin (VVG) or Weigert's resorcinol-fuchsin (Correct answer)
- Congo red
- Mucicarmine
- Oil Red O
Correct answer: Verhoeff's iron hematoxylin (VVG) or Weigert's resorcinol-fuchsin
Verhoeff-Van Gieson (VVG) stain colors elastic fibers blue-black, collagen red, and other tissue elements yellow.
Question 4: What is the purpose of the mucicarmine stain in histopathology?
- Identify iron deposits
- Highlight acid and neutral mucins, especially useful for Cryptococcus (Correct answer)
- Stain collagen fibers
- Identify amyloid
Correct answer: Highlight acid and neutral mucins, especially useful for Cryptococcus
Mucicarmine stains mucin deep rose-red and is particularly useful for identifying the mucoid capsule of Cryptococcus neoformans.
Question 5: In the Ziehl-Neelsen (acid-fast) stain, what color do acid-fast organisms (e.g., Mycobacterium tuberculosis) appear?
- Blue
- Green
- Bright red/carmine (Correct answer)
- Black
Correct answer: Bright red/carmine
Acid-fast organisms retain the carbol-fuchsin primary stain after acid-alcohol decolorization and appear bright red against a blue background.
Question 6: What color does reticulin stain (Gordon and Sweet silver method) produce for reticular fibers?
- Red
- Blue
- Black (Correct answer)
- Green
Correct answer: Black
The silver impregnation method deposits metallic silver on reticulin (type III collagen) fibers, staining them black against a golden-brown background.
ASCP Special Stains and Histochemistry 2
The Alcian blue stain at pH 2.5 is used to identify what type of tissue component?