HT Frozen Sections & Cryostat Techniques 2 — Questions and Answers
Question 1: What is the primary function of the anti-roll plate in cryostat sectioning?
- To maintain the cabinet temperature during sectioning
- To prevent the frozen section from curling as it is cut (Correct answer)
- To clamp the tissue block to the chuck
- To transfer sections from the blade to the slide
Correct answer: To prevent the frozen section from curling as it is cut
The anti-roll plate is a flat, cooled plate positioned close to the knife edge that prevents frozen sections from curling and rolling back as they are cut from the block.
Question 2: Frozen sections are particularly valuable for demonstrating which type of cellular components that are lost during routine paraffin processing?
- Nuclear DNA and chromatin
- Cytoplasmic ribosomes and rough ER
- Lipid droplets and labile enzymes (Correct answer)
- Structural glycoproteins and proteoglycans
Correct answer: Lipid droplets and labile enzymes
Lipid droplets (dissolved by organic solvents) and labile enzymes (inactivated by heat and chemicals) are best preserved using frozen section techniques that bypass standard paraffin processing.
Question 3: What is the most common artifact observed in frozen sections that degrades morphological detail?
- Tissue shrinkage artifact
- Knife chatter marks
- Ice crystal artifact (Correct answer)
- Coverslip compression artifact
Correct answer: Ice crystal artifact
Ice crystal artifact, caused by intracellular and extracellular ice formation during freezing, is the most common artifact in frozen sections and distorts cellular morphology.
Question 4: Which fixative is specifically recommended for tissue intended to demonstrate lipids in frozen sections?
- 10% neutral buffered formalin
- Bouin's fixative
- Carnoy's fixative
- Calcium-formalin (Baker's fixative) (Correct answer)
Correct answer: Calcium-formalin (Baker's fixative)
Calcium-formalin (Baker's fixative) is recommended for lipid preservation because the calcium ions stabilize phospholipids without the fat-dissolving solvents present in other fixatives.
Question 5: What does the term 'chuck' refer to in cryostat sectioning?
- The cryostat microtome knife
- The metal specimen holder onto which tissue is mounted (Correct answer)
- The anti-roll plate assembly
- The temperature control mechanism
Correct answer: The metal specimen holder onto which tissue is mounted
The chuck (specimen disc or holder) is the metal mount onto which the frozen tissue block is attached and secured for sectioning inside the cryostat.
Question 6: Frozen sections are most commonly preferred over paraffin sections for which specific intraoperative evaluation?
- Assessment of tumor histologic grade
- Determination of surgical margin status (Correct answer)
- Evaluation of hormone receptor expression
- Identification of intranuclear viral inclusions
Correct answer: Determination of surgical margin status
Frozen sections are preferred for intraoperative margin assessment because rapid results allow the surgeon to resect additional tissue immediately if margins contain tumor.
Question 7: What is the primary disadvantage of frozen sections compared to routine paraffin-embedded sections?
- Frozen sections cannot be stained with hematoxylin and eosin
- Frozen sections have inferior morphological detail due to ice crystal artifact (Correct answer)
- Frozen sections cannot demonstrate cell nuclei
- Frozen sections require significantly more expensive equipment
Correct answer: Frozen sections have inferior morphological detail due to ice crystal artifact
The primary disadvantage of frozen sections is inferior morphological detail compared to paraffin sections, mainly due to ice crystal artifact and the inability to cut as thinly.
HT Frozen Sections & Cryostat Techniques 2
What is the primary function of the anti-roll plate in cryostat sectioning?