Overheating of the paraffin used for embedding may cause:

• A. Cracking of the block
• B. Shrinkage of tissue
• C. Zoning of tissue
• D. Digestion

Answer: (A)

Overheating the embedding paraffin alters its physical behavior, making it too fluid and changing how it cools and contracts as the block hardens. This creates internal stresses within the paraffin as the wax sets, which manifest as cracks in the hardened block. Such cracks hinder sectioning and can ruin the integrity of the embedded specimen. Shrinkage of tissue is mainly caused by dehydration and fixation steps, zoning results from infiltration or temperature-related crystallization issues, and digestion is an enzymatic process affecting tissue, not a wax-related defect.