Which solvent is used for infiltration/embedding and is a different medium than Araldite?

• A. cellodin
• B. toluene
• C. xylene
• D. ethyl alcohol

Answer: (A)

The main idea is that embedding requires a medium that actually infiltrates and supports the tissue during sectioning, and there are different embedding media to choose from. Araldite is a tough epoxy resin used for embedding, especially in EM-like applications, and it requires resin-based infiltration. A different embedding medium from Araldite is celloidin, which is a distinct embedding resin (cellulose-derived) that uses its own solvent system to infiltrate tissue. That’s why celloidin best fits the idea of a different embedding medium rather than a solvent used to move from dehydration to embedding.

The other options are solvents (toluene, xylene, ethyl alcohol) used for dehydration and clearing or moving between steps, not embedding media. They don’t serve as the actual infiltrating medium for embedding like Araldite or celloidin do.