Afaf,

it depends on the task you want to carry out....you can do either cryosectioning for histology or IHC and there would be a possibility - despite not resulting in HR-results (results with "high resolution" ) to fix with fixatives (when cooled down nearly to its freezing point ) and process into e.g. paraffin as usual. The latter method not recommended but always worth a try (at least for a comparison of a mistaken task vs. results after "optimal" tissue preservation).

Second point: i) You have not defined the freezing method yyour tissue was treated (because this would be the measure of any sufficient/optimal outcome of further methods used).

And ii) You have not defined "Period of time" more in detail... so if you store tissue in (deep) frozen state (i. e. IMHO at minus 80°C and deeper) for a longer period without taking measures for a safe and physically inert length/duration of storage and (prior to and during sectioning) will treat and handle your frozen tissue incorrect/without adhering to state of the art-procedures you naturally will be confronted with perhaps problems in sectioning and adhering of sections besides poor preservation of structures and staining (HL,HC,IHC)  in your sections.  

Afaf,

it depends on the task you want to carry out....you can do either cryosectioning for histology or IHC and there would be a possibility - despite not resulting in HR-results (results with "high resolution" ) to fix with fixatives (when cooled down nearly to its freezing point ) and process into e.g. paraffin as usual. The latter method not recommended but always worth a try (at least for a comparison of a mistaken task vs. results after "optimal" tissue preservation).

Second point: i) You have not defined the freezing method yyour tissue was treated (because this would be the measure of any sufficient/optimal outcome of further methods used).

And ii) You have not defined "Period of time" more in detail... so if you store tissue in (deep) frozen state (i. e. IMHO at minus 80°C and deeper) for a longer period without taking measures for a safe and physically inert length/duration of storage and (prior to and during sectioning) will treat and handle your frozen tissue incorrect/without adhering to state of the art-procedures you naturally will be confronted with perhaps problems in sectioning and adhering of sections besides poor preservation of structures and staining (HL,HC,IHC)  in your sections.  

Dear Afaf,

I would not recommend to take your frozen tissue and put it into formalin. This will lead to freezing artefacts and evaluation might be difficult. As a last resort, however, it is still a possibility.

You can of course use frozen tissue for further analysis. However, if this is possible in your case is difficult to say without further information. 

How have you frozen your tissue? Have you put it into physiological saline or OCT compound? At what temperature and for which length of time has it been stored? What is it you intend to do with the tissue?

Regards

Gerald Niedobitek

thanks a lot for both of you 

first :- samples were transported to the lab in an ice box then the were placed directly in the deep freezer at -20 c without being treated with any copound or physiological saline.

secon:- samples kept there since ( between 31 to 66 days).

third:- we want to inspect the  histopathological alterations in muscle and liver such glycogen , collagen fibers etc).

I suspect this is not going to work satisfactorily on the tissues you have stored. Storage at -20°C is not optimal. Frozen tissue samples should be placed into saline or OCT and stored at around -80°C following snap freezing in liquid nitrogen. 

Better yet, if you want to analyse morphology, fix tissues in 4% buffered formalin sollution for appr. 24 h and embedd into paraffin blocks using standard histopathologcal techniques.

@ Gerald (and Afaf):  I  agree with

,    and   

Don't agree with:

instead:  initial ("HR"- *) ) freezing as for e.g. (human) muscle biopsies in clinical settings: use of precooled (= i) using either dry ice or, much better ii) cooled down to around/nearly its freezing point = –255.8°F = –159.9°C = 113.3°K. ) isopentane.  After optimal =( *) "HR"-  ) freezing: storage in proper manner in at least -(minus) 80 degr.C). There are published and mentioned  a lot of methods using isopentane out in the wild. Best wishes and regards, WM

I absolutely agree with dr.Muss.The main aid of fixation is to preserve tissues by stopping autolitic changes. Placing samples in saline prior fixation allows autolysis to proceed and freezing before fixation causes many structural changes in tissues(according to my practice).

"Frozen tissue samples should be placed into saline or OCT and stored at around -80°C following snap freezing in liquid nitrogen."

This was not phrased properly. Fresh tissue should be placed into saline or OCT immediately prior to snap freezing in liquid nitrogen and then stored at -80°C. 

The slow freezing at -20 C will already lead to artefacts. Isopentane is quite ok but fish contains quite more water, compared to human samples, so anyway there will be some of them.