ASCP Special Stains and Histochemistry 2

Question 1

The Alcian blue stain at pH 2.5 is used to identify what type of tissue component?

Accepted Answer

Acid mucopolysaccharides (acid mucins)

Answer

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?

Accepted Answer

Blue-black

Answer

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?

Accepted Answer

Verhoeff's iron hematoxylin (VVG) or Weigert's resorcinol-fuchsin

Answer

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?

Accepted Answer

Highlight acid and neutral mucins, especially useful for Cryptococcus

Answer

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?

Accepted Answer

Bright red/carmine

Answer

Acid-fast organisms retain the carbol-fuchsin primary stain after acid-alcohol decolorization and appear bright red against a blue background.

ASCP - Histotechnician Test Practice Test