The platform is equipped with Leica EM AFS2 systems for freeze substitution and low-temperature sample processing.
Freeze substitution is generally performed after high-pressure freezing or another cryofixation method. While the specimen remains at very low temperature, vitrified water is gradually replaced with an organic solvent, commonly acetone or methanol. Fixatives, stains, or contrasting agents may be incorporated into the substitution medium according to the protocol.
The temperature is then progressively increased before resin infiltration, embedding, and polymerization.
Freeze substitution combines the structural preservation obtained through rapid cryofixation with the practical advantages of resin embedding and room-temperature ultramicrotomy.