Yes, you're right...it definitely came out wrong and that's a much better way to put it. Thank you for letting me know and for the suggestion.

For parafin sections, you can fix them in 4% PFA, 24 hours should do it, depending on how thick the tissue is, and then was and store in 70% ETOH.  They should keep for quite a while in that manner. For DNA an RNA -80 but for the RNA, even -80 might not be good enough.  If you need the RNA I would extract it from the tissue immediately and then freeze it at -80, then you can use it when you need it.  DNA is far more stable so it should be okay at -80. For immediate imaging, you should fix the tissue in PFA and then process

For RNA isolation it can be put in TRIZOL and kept in -80 freezer. DNA is more stable and  can be kept as such in -80 freezer.

Additionally, I would like to highlight a new technology enabling robust RNA detection in tissues  https://acdbio.com/science/applications/research-areas/cancer 

Best and easy way to store your samples in -80c with proper labelling and covering.

If you want to see the GFP, you need immediate imaging. If you fix the tissue with PFA, GFP fluorescence is lost. After fixation in PFA, you should wash them in PBS, de-hydrate in put in paraffin. On paraffin sections, you can detect the GFP with antibody staining and do multiple labelling (see example below). If you do not have the time to do the embedding right away, you can leave the tissue in 0.4%PFA @4°C for a week. Liquid nitrogen and storage at -80°C is ok for RNA, DNA and protein. For cryosections it is not optimal as most tissues will break when you drop them in nitrogen.

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