General Research Topics => General Discussion => Topic started by: JSSVSU on July 19, 2013, 10:27:31 AM

Title: Deparaffinization of entire blocks
Post by: JSSVSU on July 19, 2013, 10:27:31 AM
I have rodent brain hemispheres that I have embedded in paraffin. These are already in blocks and ready to be sectioned. However, I would like to try a new clearing technique (SeeDB) with some of the extra hemispheres that I am not planning on slicing.

Is there a good method for deparaffinization entire blocks (not just sections) that anyone can share? Any general advice?

Thanks in advance.
Title: Re: Deparaffinization of entire blocks
Post by: gula on July 19, 2013, 01:29:48 PM
In general you can deparaffinize with the same reagens you have used in the processing - only the other way round.
warm the block - solve paraffin in xylol or similar - then ethanols...

I wouldn't recommend it just for fun or trial, because every additional time in xylen and absolute ethanol will harden the tissue more and more.
It makes sense, if your blocks aren't fully penetrated with paraffin or still contaminated with xylen or ethanol or even water.

Processing to paraffin - and - bringing blocks back to ethanol - and - clearing and impregnation again with paraffin doesn't bring the same result as only one process.
So it would be a faulty comparison to your new clearing reagens.

Do you have problems with sectioning the brains? If they are mushy in the center, you can improve it, by bringing the tissue back into warm paraffin for an addintional time (few hours).
If the tissue is dry-white and hard, overdehydration has happend and bringing blocks back again into dehydrating reagens is a bad idea. Here moistering with little water directly onto the faced block surface will help more.