High pressure freezing and freeze substitution for immuno
To avoid the occurrence of artifacts, which can be introduced by chemical fixation, a sample can instead be vitrified under very high pressure in liquid nitrogen.
After high pressure freezing, as described for ultrastructure, a very gentle freeze substitution cocktail is applied followed by embedding in a hydrophilic acrylic resin. Labelling is performed on-section. This technique combines excellent ultrastructure and antigen preservation.