frozen section formalin fixation - (May/12/2008 )

what is better? to fix with formalin then snap freez the tissue and cut, OR, freez cut and then fix with formalin.....
and why?


and what about sucrose after formaline?

thanks

Neither: They are different methods used for different things. There should be no need to fix and freeze your tissue. Cryosectioning is used to detect rapidly morphology of tissues (especially for rapid diagnosis), but has issues with thick sections and loss of fine morphology. Can also be used if your antigen is hard to detect.

Fixed tissue allows fine morphology to be observed, but takes longer to do and may mask some antigens with the formalin.

freeze, cut, place on slide, keep frozen (-80) then fix immediatly prior to immuno (or whatever)
you can use acetone, acetone/methanol, formaldehyde(from paraformaldehyde - freshly made - 0.4g in 10ml pbs, heated + 2ul 5molar NaOH) depending on antibody

tissue MUST be fixed however before you stain or your results will be meaningless

dom

why would you want to?

a dehydration fix would shrink the tissue and compromise cutting - pfa may be incompatable with later antibodies

we do it this way to increase later "tweaking" of the experiment - leaves our options open

so unless you have a really important reason to fix first - dont

dom