Histology Techniques & Technology Flashcards

What is the role of a mordant in histological staining?

Answer: To link the dye to the tissue component

A mordant forms a bridge between the dye and the tissue, creating a stable dye–mordant–tissue complex and intensifying the stain.

In the Masson trichrome stain, collagen fibers are demonstrated in which color?

Answer: Blue or green

Masson trichrome stains collagen blue (with aniline blue) or green (with light green), while muscle stains red and nuclei stain black.

Which stain is the gold standard for demonstrating amyloid deposits in tissue sections?

Answer: Congo red

Congo red stains amyloid salmon-pink and shows apple-green birefringence under polarized light, which is pathognomonic for amyloid.

The Prussian blue (Perls') reaction is used to detect which substance in tissue?

Answer: Ferric iron (hemosiderin)

Perls' Prussian blue reaction converts ferric iron to ferric ferrocyanide, producing a bright blue precipitate that identifies hemosiderin deposits.

Diastase pre-treatment before PAS staining is used to confirm the identity of which tissue component?

Answer: Glycogen

Diastase (amylase) digests glycogen; PAS-positive material that disappears after diastase pre-treatment is confirmed as glycogen.

Which fixative is preferred when performing frozen sections for lipid demonstration?

Answer: Unfixed fresh-frozen tissue or formalin-fixed frozen sections

Lipids are dissolved by organic solvents used in routine paraffin processing, so frozen sections from unfixed or formalin-fixed (not paraffin-processed) tissue are required.

In immunohistochemistry, heat-induced epitope retrieval (HIER) is performed primarily to reverse which processing effect?

Answer: Cross-linking of proteins caused by formalin fixation

Formalin creates methylene bridges between proteins that mask epitopes; HIER uses heat and buffer to break these cross-links and unmask the epitopes.