Frozen Section Protocol

• 1. Place the tissue in a small sealed box (if the tissue is too small, to hold it, pour in some embedding reagent like OCT);
• 2. Froze the box in liquid nitrogen (approximately 10-20s needed);
• 3. Transfer the tissue to frozen section machine or store at -80°C for future use;
• 4. Equilibrate at -20°C for approximately 15 minutes to prevent cracking of the tissue block when sectioning;
• 5. Section the block at a range of 6-8 µm and place on slides;
• 6. To help tissue adhere, air dry sections for a few minutes before fixing.

Advantages:

• 1. Frozen section nornally takes less time than paraffin section due to simpler procedures.
• 2. In frozen section process, the activity and epitope of target antigens can be well preserved compared to paraffin section, thus a antigen retrieval procedure is not usually needed in frozen section.

Disadvantages:

• 1. The tissue could be less morphologically interacted than paraffin section and antigen signals might be more dispersed in the final scope.
• 2. The section slides might only be stored at low temperature like -80°C.