There are divers aspects. First it is important to open and clean the colon. The time between surgery and fixation should be as short as possible. For good morphology fixationtime has no limit in usual practice. For advanced techniques like ihc and molpath standardization is important. 24 to 72 hours are a usual time, but for ihc a week should make no problems with adequate antigen retrieval. Molpath for FFPET usually deals with such a fixationtime. RNA may be affected most.

Gudrun Lang Thank you, Professor, for your detailed answer. It will help me a lot.