During microtomy, it is noted that most of the tissue is very hard and shrunken. One of the first things to check to prevent its happening in the future is the:

• A. Temperature of the infiltrating paraffin
• B. Section thickness
• C. Blade sharpness
• D. Fixative duration

Answer: (A)

The main idea is that heat-related artifacts during embedding are a common cause of tissue appearing hard and shrunken in microtomy. If the infiltrating paraffin is overheated, tissue components can be distorted as the embedment occurs, and when the block cools, the tissue can contract, making it look hard and shrunken. Checking and maintaining the paraffin at the correct infiltration temperature (using fresh, properly heated molten paraffin and avoiding overheating) helps prevent these heat artifacts across most tissue types. If the paraffin temperature is appropriate and the problem persists, other factors like section thickness, blade sharpness, and fixative duration can then be evaluated, but they’re less likely to cause widespread hard/shrunken tissue in routine cases.