Yes, Michels solution can be stored at room temperature, but refrigerated is probably better.  It should not be frozen.  See:

http://www.statlab.com/wordpress/wp-content/uploads/2017/04/michels-transport-medium-technical-data-sheet.pdf

http://www.ihcworld.com/_faq/histology-faq/fixation/f9.htm

Dear Janith: is it the following Michels solution you mean/you would like to use? Since I am interested to know (or - at least - to verify) what Michel's fixative solution is:

Michel's Buffer/ Transport Medium

Solutions required to make Michel's Buffer are:

1M  Potassium Citrate H2O                  32.4g

    Distilled water    100ml

0.1M  Magnesium Sulphate 7H2O        2.43g

    Distilled water   100ml

0.1M  N-Ethylmaleimide                          1.25g

    Distilled water   100ml

1M   Potassium Hydroxide                      5.61g

     Distilled water    100g/ml

Stock Buffer Solution

1.0M   Potassium Citrate       2.5ml

0.1M   Magnesium Sulfate    5.0ml                                                                                       0.1M  N-Ethylmaleinmide     5.0ml

Distilled water                      87.5ml

Adjust to pH 7.0 with 1M Potassium Hydroxide

Working Buffer [?] Solution [fixative?] 

100ml Michel's Buffer stock solution

+ 55g Ammonium Sulphate 

Dissolve and adjust to pH 7.0 with 1M Potassium Hydroxide.

Store all solutions at 4°C.

The working solution will keep almost indefinitely, though it is sensible to make up volumes that are likely to be used within a reasonable time.

For a piece of tissue, approx. 4mm cube, a volume of 2-3ml is sufficient.  Whilst solutions should be stored at 4°C, it is not necessary to remain at 4°C whilst being transported. No deterioration will occur to the tissue. On receipt of a specimen in buffer solution, store at 4°C until ready to proceed.

Specimens received in Michel's Buffer need to be washed in a washing buffer [*)], with three changes of 10 minutes each. Place tube on a rotating mixer to ensure all vestiges of Michel's buffer are removed. The specimen is gently blotted before freezing.

[*) Coons Washing Buffer Stock Solution:                                                                       Disodium hydrogen orthophosphate 4.25g / 2.125g                                               Sodium chloride 43.5g / 21.75g                                                                                     Potassium dihydrogen orthophosphate 2.7g / 1.35g                                                   Distilled water 1000ml / 500ml

Adjust to pH 7.1 - 7.3 with 1N sodium hydroxide

 [Coons] Washing Buffer Working Solution

Dilute stock solution 1 in 5 with distilled water. Check pH and adjust if necessary. "

The former recipe and description I found in 2008 when searching for transportation fluid/buffer/fixation solutions for skin....(e.g. Michel, B, Milner,Y and David, K., Journal Invest. Dermatol., Vol 59, 1973, p449, "Preservation of tissue fixed immunofluorescence in skin biopsies of patients with LE and bullous disease"- (Prelim report) and when searching for a recipe, I found:  MICHEL’s Buffer

@ http://mcrf.jcs.anu.edu.au/histology/frozensections/    [The John Curtin School of Medical Research; Microscopy and Cytometry Resource Facility) .

In 2010     I found another source for (both) the solution(s)[Disclaimer: no affiliation to or financial interest in any supplier company mentioned in the following)  :

Archive Histonet-Listserver ( Jan 2001):

From:  "Diane G. Miller"

I agree with Gail.  You can purchase from NewComer Supply as well, Phone 1-800-383-7799

Diane

 ----- Original Message -----

From: "Gayle Callis"

To: "Bonnie P Whitaker" ;

Sent: Friday, January 12, 2001 8:01 AM

Subject: Michel's fixative

After making this up with the expense of chemicals, plus storing them, it was much easier to buy it in bulk from Poly Scientific, a histo reagent supplier, don't have the 800 number offhand, but it was reasonable for price and quantity.  The buffer is sold separate from fixative, need both which you are probably already aware of.

 Gayle Callis,

Veterinary Molecular Biology; Montana State University; Bozeman MT 59717-3610

phone: 406 994-4705; 406 994-4303

 -

At 02:28 PM 1/12/01 -0600, you wrote:  

This is what I have:

Michels Buffer

1M potassium citrate, pH 7.0              2.5 ml

0.1M magnesium sulfate                     5.0 ml

0.1M N-ethyl malemide                       5.0 ml

d H2O                                                87.5 ml

* Mix well and store at 2-8C.   Exp. 1 year

Michel's Fixative 

Michel's Buffer                                    100ml                                                                 ammonium sulfate                                55gm

Adjust pH to 7.0-7.4 with 1M KOH.  Store at 2-8C.  Exp. 1 year

Bonnie Whitaker, UT--Houston    - End of citation - 

Hope this helps anyway....

Yes, dear Dr

This important link

http://www.ihcworld.com/_faq/histology-faq/fixation/f9.htm