Additives to paraffin increase which property for embedding hard and dense tissue?

• A. Increases hardness and support for hard and dense tissue
• B. Increases brittleness
• C. Reduces hardness
• D. No effect

Answer: (A)

Hardness and support of the embedding medium are what matter when you’re working with hard and dense tissues. Paraffin by itself can be too soft to hold the tissue securely during sectioning, leading to tearing or compression artifacts. By adding materials that increase the rigidity of the paraffin, the block becomes firmer and provides better backing for dense structures. This additional hardness lets the microtome slice thinner, more uniform sections with fewer deformations, which is essential for hard tissues like bone or calcified areas. The goal of these additives is specifically to boost the block’s rigidity to protect the tissue and improve section quality.