cracking paraffin sections

Dr Engelbert Buxbaum engelbert_buxbaum at
Thu May 20 12:49:58 EST 2004

Amy wrote:

> I need some advice as to how I can stop my paraffin sections from
> cracking or shriveling when I am staining.  I do not know when the
> sections are being destroyed.  I consistently get tissue that is
> useless.  Please give me any feedback.

Unfortunately with your description (or the lack of it) it is difficult
to diagnose the problem. 

Paraffin sections can crack during cutting, if the temperature of the
block is too low. On the other hand, if the temperature is too high, the
paraffin smears, so you need to fiddle a little with the melting point
of your paraffin and your room temperature. Cracks may also be caused by
insufficient removal of the intermedium. Change the paraffin twice
before blocking.

The next critical step is stretching of the sections. For this the
sections are placed onto a drop of water on the microscopic slide and
carefully warmed just below the melting point of the paraffine. You can
watch the section flatten, the effect is quite striking. Do not melt the
paraffine during this procedure.

Now you can remove most of the water with a little filter paper and
allow the section to dry onto the slide. Normally the section sticks
well enough for the following dehydration and staining steps. If they
don't, you can coat the slides with a mixture of egg white and glycerol.
Allow to dry and then use the slides for the procedure described above.

As with most procedures involving microscopy, it is best to consult the
following book about technical details:

        AUTHOR= {B. Romeis},
        TITLE= {Mikroskopische Technik},
        YEAR= {1989},
        PUBLISHER= {Urban und Schwarzenberg},
        ADDRESS= {München},
        EDITION= {17},
        LANGUAGE= {dt}

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