When transitioning from Optimal Cutting Temperature (O.C.T.)-embedded tissue to paraffin embedding, here’s how you can effectively remove the O.C.T. and proceed with paraffin fixation:

Remember that the choice of fixative depends on the antigen and the desired detection technique. Proper fixation ensures reproducible staining and successful antigen detection. If you encounter any difficulties during the process, consider collaborating with labs that specialize in histology services4

Hi Omar, Thanks for explaining and suggesting the OCT removal and fixation by Paraffin.

We Paraffin embedded tissues but they were ruined, so we are trying to retrieve tissue from OCT and fix with Paraffin.

I will follow your suggestion.

Unfortunately, once the tissue is frozen you're kind of out of luck. You can try a slow thaw and then repeated PBS washes to remove the OCT and sucrose cryoprotection.

If the tissue is just in OCT and not frozen or just in sucrose, that's significantly easier. You can get a good idea how how much sucrose is left in the tissue by using different gradients. If the tissue still sinks in let's say, 5% sucrose, you have some more washes to go. Once the tissue is fully cleared of sucrose, I would fix again (especially if you're thawing a block) for another 24 hours before paraffin processing.