Dear Sharma,
     I think there is a hard tissue subgroup of HistoNet that may have ideas 
to rescue you.  Is this correct, HistoNetters?  Also, I have heard reports of 
histologists doing plastic sectioning for large pieces of undecalcified hard 
tissue.
     We frequently get animal digits, particularly canine, and have to 
section the nail.  Of course, this is substantially smaller than a hoof, but 
the material is similar.  On the off chance that this might help you, I will 
tell you how we handle our hard tissues.  For any bone or nail specimens we 
receive, we decalcify the specimen by soaking it in at least a 10:1 ratio of 
5% nitric acid to specimen volume.  We change the solution daily and 
decalcify for several hours to as long as 2 weeks depending on the tissue.  
Removing any unnecessary tissue is helpful for penetration.  After the tissue 
feels soft, we paraffin process it.
     After processing and embedding, if the sample is still too hard to cut 
well, we face the block and soak the surface of the block on a gauze sponge 
soaked in 5% nitric acid solution in a closed container for several minutes.  
I then switch to a thick microtome blade and if I cut slowly and carefully, I 
can usually get several good sections.  Using charged slides is usually 
necessary for the section to remain adhered to the slide during the staining 
process.
     Good luck hoofing it!

Kim Atkin

Histology Laboratory Supervisor
Angell Memorial Animal Hospital
350 South Huntington Avenue
Boston, MA 02130


Inforamtion on cutting hard tissues
From: ssharma@watsonpharm.com 

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Hello everybody,

As part of ongoing research at our company I was trying to cut uniform cross
sections of bovine hooves across the horizontal plane. We recently bought a 
new
sliding microtome (HM 440E, Carl Zeiss, Inc.) and were using it with a
Tungsten-carbide knife.  Unfortunately the tissue is much harder than what we
expected and we were unsucessful. I was wondering if anyone out there had a
similar experience with this kind of material or with some other hard 
material.
I would be grateful if someone could give me tips about any how to cut hard
materials or inform me of any softening methods used for hard keratinous
materials.

I am new to the process of microtomy and also a new addition to this list.

Thanks for your time.

Sanjay Sharma