Once the tissues are in any ethanol or methanol you will never be able to get a frozen section. The only way I have been able to salvage anything like this was to place the OCT block into 10%BNF on a rotator and let them thaw/fix and process into a FFPE block.
If they cannot use FFPE because of the experiment I would say they need to start over. This time, freeze the sample, NO METHANOL FIRST. Do the fixation as a post fix OR fix in an aqueous fixative such as 4%para or 10%BNF, sucrose protect and then freeze. Believeme, I have tried to get this to work in so many ways and all experts I consulted told me the exact same thing. The mehthaol will not allow the sample to freeze hard enough to cut. They don't even want to use a slurry with methanol to freeze it the OCT block. The tissue will absorb enough of that methanol to prevent good frozen sectioning. Good Luck.... Colleen Forster HT(ASCP)QIHC On Fri, Jul 12, 2024 at 11:09 AM Davoli, Katherine A via Histonet < histonet@lists.utsouthwestern.edu> wrote: > The initial freeze isn't usually the problem. It's what happens when it > warms back up to Cryostat cutting temperatures of -20 or -25. > You'd need to get the methanol out of the tissue completely because it > causes the support to melt at the temperatures the Cryostat cuts at. > > And unfortunately I have not found a method that fully removes ethanol or > methanol from a tissue sample that would then allow me to freeze and cut > it. If someone else replies with one I will genuinely be delighted because > I have this problem a lot. > > Katherine Davoli, MDiv, HTL(ASCP)cm (they/them/theirs) > Lab Manager, Tissue Culture & Histology Cores, U. Pitt Dept of > Ophthalmology > 7.373 UPMC Mercy Pavilion 1622 Locust St.,Pittsburgh PA 15219 > (412) 624-8508 this number cannot receive texts > > -----Original Message----- > From: Charles Riley via Histonet <histonet@lists.utsouthwestern.edu> > Sent: Friday, July 12, 2024 12:04 PM > To: histonet@lists.utsouthwestern.edu > Subject: [Histonet] Cryotomy help > > I have a researcher who is trying to mass spectrometry on frozen tissue > sections. They submitted the sample in methanol and even after sitting in a > -80 freezer overnight the samples are too soft to section. > > Does anyone have any tips on how to harden the tissue for sectioning that > won't damage the results for mass spect (I was thinking liquid nitrogen but > want to be sure it won't damage the results)? > _______________________________________________ > Histonet mailing list > Histonet@lists.utsouthwestern.edu > http://lists.utsouthwestern.edu/mailman/listinfo/histonet > > _______________________________________________ > Histonet mailing list > Histonet@lists.utsouthwestern.edu > http://lists.utsouthwestern.edu/mailman/listinfo/histonet > -- Colleen Forster HT(ASCP)QIHC BLS Histology and IHC Laboratory Jackson Hall, Room 2-155 321 Church St. SE Minneapolis, MN 55455 612-626-1930 _______________________________________________ Histonet mailing list Histonet@lists.utsouthwestern.edu http://lists.utsouthwestern.edu/mailman/listinfo/histonet