Which solvent is used for infiltration/embedding and is Araldite?

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

Answer: (A)

The main idea is that embedding requires a resin that can permeate the tissue and harden to form a stable block for sectioning. Araldite is an epoxy resin used specifically as the embedding medium; after dehydration and clearing, the tissue is infiltrated with Araldite and then polymerized to produce a rigid block suitable for thin sectioning. The other substances listed are solvents used earlier in processing—ethylene alcohol for dehydration and xylene or toluene for clearing and transitioning to embedding—not the embedding medium itself. So Araldite is the material that actually infiltrates and embeds the tissue.