Abstract
Preserving structurally intact tissue through proper tissue fixation and cryopreservation minimizes tissue autolysis, desiccation, and enzymatic degradation. In this protocol, we describe the use of an optimized fresh freezing technique that cryopreserves the tissue and favors the retention of the natural protein structure of antigens. We also detail the use of cold, low-concentration paraformaldehyde (PFA) fixation to enhance tissue morphology and detection of fluorescent proteins, such as GFP and TdTomato, in tissues of genetically engineered mice. For complete details on the use and execution of this protocol, please refer to Chen et al. (2022)1 and El-Naccache et al. (2022).2.