Which material is used as the embedding medium in this processing protocol?

• A. Epoxy resin
• B. Gutta-percha
• C. Paraffin wax
• D. Acrylic resin

Answer: (C)

Embedding medium must provide firm support for thin sectioning and be compatible with routine staining. Paraffin wax fits this need for standard light microscopy: after dehydration and clearing, tissue is infiltrated with molten paraffin, which then solidifies into a uniform block that can be trimmed and cut into thin sections for mounting. This yields good enough preservation of tissue architecture for common stains like H&E and is easy to handle and cost-effective. Other options are used in different contexts: epoxy or acrylic resins create much harder blocks suitable for electron microscopy or special plastic sections, not typical light-m microscopy. Gutta-percha is a dental filling material, not an embedding medium.