Re: Cryostat phenomenon

From:Connie McManus <>

At 11:17 AM 5/17/01 -0800, Karen Larison wrote:
>We first embed them in a 
>melted agar-sucrose matrix, which allows us to orient them very 
>precisely within the block for serial sectioning.  

What is the formula for the agar and sucrose?  I am interested in trying
this.  Do you need to let the tissues infiltrate in the agar for a while?

Connie McManus

We then let the 
>block solidify and then sink it in in sucrose before sectioning.  The 
>nice thing about these agar blocks is that they ribbon nicely.  You 
>can cut a series of sections with the antiroll plate, then use a 
>brush to straighten them out, and then pick them up.  Using this 
>method, we are better able to position these tiny sections on a 
>slide, we are less likely to experience "leaping" sections, and we 
>can get 70-100 sections on one slide in very short order!
>We also use Tissue Freezing Medium (made by TBS, available from 
>Fisher Scientific) to adhere our agar block to the chuck, and find 
>that this curls less, and appears to have less static problems than 
>Karen in Oregon
>>  Has anyone encountered a phenomenon that I occasionally get
>>with cryostat frozen sectioning. I assume it is due to static
>>electrical charges? the sections tend to "leap" from the knife edge
>>onto the slide, the slide may be some several centimeters from the
>>section/knife holder.
>>There is no logic or consistency to this, irrespective of tissue,
>>fixation, temperature, type of slide; but if it is going to happen then
>>you can be sure it is when cutting a tiny piece of tissue where
>>every section is required! It will often disappear as suddenly as it
>>started, sometimes quite impressive when a section fly's several
>>cms. to the slide and occasionally lands flat and crease free!
>>Any idea's?Oh, and I don't wear nylons (not in work anyway).
>>Terry Hacker,
>>Medical Research Council,
>>Oxfordshire, OX11 ORD
>>01235 834393 x360
Connie McManus
Veterinary Diagnostics Lab
Utah State University
Logan, UT

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