Fresh tissue preservation for mid to long term. - (Dec/29/2014 )

I was wondering if storing fresh tissue (already snap frozen in liquid nitrogen) in a -80 frezeer is acceptable for mid to long term storage. The tissue would be used for RNA analysis and H&E/IHC stainings.

Depending on the tissue type it may be appropriate for RNA. Gut, pancreas and liver would be the exceptions to this (maybe others too), as they are full of RNases. should be fine for tissue sectioning.

So for those three tissues liq. nitrogen vapor is a must? So far I only have lung and breast tissue (tumors really). 

One other question, I am used to freezing/embedding tissue in OCT by putting the mold/tissue/OCT in liquid nitrogen vapor for a few mins until the OCT is completely frozen. However all the protocols I find online use a dry ice bath. Is there anything wrong with the way I do it besides safety concerns in handling liq nitrogen?

For lung and breast, -80 should be fine for RNA and tissue sectioning. Your embedding method should work fine, the dry-ice bath thing is equivalent to a -80 anyway.