HT Frozen Sections & Cryostat Techniques 1 — Questions and Answers
Question 1: What is the primary purpose of a cryostat in histology?
- To fix tissue rapidly with chemical agents
- To section frozen tissue at controlled low temperatures (Correct answer)
- To dehydrate tissue for paraffin embedding
- To stain sections at sub-zero temperatures
Correct answer: To section frozen tissue at controlled low temperatures
A cryostat is a refrigerated microtome that sections frozen tissue at controlled low temperatures, preserving labile enzymes and lipids that would be destroyed by standard processing.
Question 2: What temperature range is typically maintained inside a cryostat cabinet for routine soft tissue sectioning?
- 0°C to -5°C
- -8°C to -12°C
- -15°C to -25°C (Correct answer)
- -35°C to -45°C
Correct answer: -15°C to -25°C
Cryostat cabinets are typically maintained between -15°C and -25°C, which is optimal for sectioning most soft tissues without causing them to shatter.
Question 3: Which embedding medium is most commonly used to support tissue for frozen sections in a cryostat?
- Paraffin wax
- Optimal Cutting Temperature (OCT) compound (Correct answer)
- Celloidin
- Glycol methacrylate resin
Correct answer: Optimal Cutting Temperature (OCT) compound
OCT (Optimal Cutting Temperature) compound is the standard embedding medium for cryostat sectioning because it supports the tissue block without interfering with most staining procedures.
Question 4: What is the primary advantage of frozen sections over routine paraffin-embedded sections?
- Superior morphological detail and nuclear clarity
- Better long-term archival storage of tissue
- Rapid preparation time enabling intraoperative diagnosis (Correct answer)
- Ability to cut thinner sections
Correct answer: Rapid preparation time enabling intraoperative diagnosis
The primary advantage of frozen sections is rapid turnaround (15–20 minutes), allowing surgeons to receive an intraoperative diagnosis without significantly prolonging the procedure.
Question 5: Which type of tissue component is BEST demonstrated using frozen sections rather than paraffin-embedded sections?
- Nuclear chromatin and DNA
- Cytoplasmic ribosomes
- Lipids and neutral fats (Correct answer)
- Structural proteins such as collagen
Correct answer: Lipids and neutral fats
Lipids are dissolved by the organic solvents used during paraffin processing, so frozen sections must be used to demonstrate lipid droplets and neutral fats in tissue.
Question 6: Which staining method is most commonly used for rapid staining of intraoperative frozen sections?
- Hematoxylin and eosin (H&E) (Correct answer)
- Periodic acid-Schiff (PAS)
- Masson's trichrome
- Giemsa stain
Correct answer: Hematoxylin and eosin (H&E)
H&E is the most common rapid stain for frozen sections because it provides adequate nuclear and cytoplasmic detail for diagnostic purposes within a few minutes.
Question 7: What is the typical section thickness range for routine diagnostic frozen sections?
- 1–3 micrometers
- 4–6 micrometers
- 8–12 micrometers (Correct answer)
- 20–30 micrometers
Correct answer: 8–12 micrometers
Frozen sections are typically cut at 8–12 micrometers because frozen tissue cannot be sectioned as thinly as paraffin-embedded tissue and requires greater thickness for intact sections.
HT Frozen Sections & Cryostat Techniques 1
What is the primary purpose of a cryostat in histology?