sucrose pretreatment for frozen sections

J. A. Kiernan jkiernan at
Thu Aug 24 09:17:17 EST 1995

In article <DDs1yt.L76 at> af826 at FreeNet.Carleton.CA (Christine McGregor) writes:
>From: af826 at FreeNet.Carleton.CA (Christine McGregor)
>Subject: sucrose pretreatment for frozen sections
>Date: Wed, 23 Aug 1995 18:56:53 GMT

>I usually soak formalin-fixed rat brains in 20 % sucrose solution for 24 hours
> prior to frozen-sectioning. Can anyone tell me if there is an upper limit to
> the time the brain can be left soaking...will the formalin fix leach out as
>it does in water? Will there be a loss of morphological detail or artefact
>from microbes? I am wondering about the effect of a week or two.(refrigerated,
>of course).

   If the tissue has actually been fixed by the formaldehyde (this means
   48 hrs minimum) you can keep in in the cryoprotectant sucrose solution
   for several weeks (my experience), probably longer, with no infection
   or deterioration of structure.
     Sucrose treatment is often used after brief treatments with 
   formaldehyde (perfusion and a few hours of immersion), which cause
   only partial cross-linking of proteins. The concentration of HCHO
   is greatly reduced by diffusion and dilution in the sucrose solution.
   Moulds can grow after several days, and cytoplasmic textures are spoiled
   by autolysis.  So if you must use brief, inadequate fixation, don't
   store the specimens in sucrose for long.

                                     John A. Kiernan
                                     Department of Anatomy
                                     Univ. of Western Ontario
                                     LONDON, Canada  N6A 5C1
                                     e-mail: kiernan at

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