The issue in the image is most likely due to which cause?

• A. An improperly clamped block
• B. A dull blade
• C. Overdehydration
• D. Too thick embedding

Answer: (A)

Block security in the microtome is essential to prevent movement during sectioning. When the block isn’t properly clamped, it can slip or tilt as the knife advances, producing artifacts such as chatter marks, tearing, and irregular ribbon thickness. The image showing those movement-related signs fits this scenario, pointing to improper clamping as the cause. A dull blade would mainly give rough, torn edges within individual sections rather than a coordinated movement artifact. Overdehydration makes tissue brittle and prone to cracking, not block movement. Too thick embedding results in uniformly thick sections and poor adhesion, not slippage during cutting.