Many laboratory researchers are accustomed to storing tissue wax blocks for a long time at room temperature after sectioning, and the tissue after sectioning is prone to antigen loss for long-term storage at room temperature. 

Some studies have found that when sections are stored at room temperature for more than 3 months, immunohistochemical staining results are weakened or even negative. Therefore, some scholars have carried out new and old slice preservation time control experiments. 11 different tissue wax blocks were selected and 10 pieces were cut continuously for a total of 110 pieces per case, and placed in room temperature air for 1 month, 3 months, 6 months, and 1 year, and then the control experiment was carried out with new sections. The experimental results showed that when stored at room temperature for 3 months after wax sectioning, the sensitivity of antigens to most antibodies decreased by 50%, and the antigen loss of some sections was more. Most antibodies did not show positive results after 6 months of sectional storage, and only a few sections had weak positive expression after storage for more than 1 year, especially nuclear expression antigen loss was more prominent. 

The reason may be related to oxidation, so in practical work, wax sealing sections and -20 degrees cryopreservation tissue sections can be used to avoid antigen loss, or paraffin tissue blocks can be stored at 4 degrees, and then sectioned when used, which can greatly reduce the antigen loss rate.