Specimen Preparation Flashcards
7 cards from real Histology Certification practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Specimen Preparation flashcards as text
Which of the following tissues requires special handling with osmium tetroxide fixation?
Answer: Tissue for transmission electron microscopy
Osmium tetroxide is a secondary fixative used in electron microscopy that preserves and stains lipid membranes for ultrastructural examination.
A tissue block faces (trims) unevenly, showing tissue only on one side. The most likely cause is:
Answer: Incorrect tissue orientation during embedding
Improper tissue orientation in the mold causes asymmetric block facing, resulting in uneven sections.
The recommended minimum fixation time for a 3–4 mm thick tissue section in 10% NBF is:
Answer: At least 6–12 hours, optimally 24 hours
CAP guidelines recommend at least 6–12 hours of fixation for standard tissue, with 24 hours considered optimal for consistent IHC results.
Which embedding medium is used for cutting thin sections (50–100 nm) for electron microscopy?
Answer: Epoxy resin (e.g., Spurr or Epon)
Epoxy resins provide the hardness necessary to cut ultrathin sections required for transmission electron microscopy.
Tissue sections showing 'holes' or 'vacuoles' throughout are most likely caused by:
Answer: Residual water during paraffin infiltration
Residual water from incomplete dehydration vaporizes during paraffin infiltration, leaving vacuoles or holes in sections.
What is the purpose of poly-L-lysine or APES coating on glass slides?
Answer: To enhance tissue section adhesion, especially for IHC
Positively charged coatings such as poly-L-lysine improve electrostatic adhesion of negatively charged tissue sections, preventing detachment during IHC protocols.
When grossing a mastectomy specimen, the standard method to ensure adequate formalin penetration into breast tissue is:
Answer: Serial parallel bread-loaf sectioning at 5–10 mm intervals before fixation
Bread-loaf sectioning exposes interior tissue to formalin, ensuring rapid and uniform penetration throughout the thick specimen.