Hard Tissue Committee/NSH and horse hooves

From:Gayle Callis <uvsgc@msu.oscs.montana.edu>

The Hard Tissue Committee is available to all members of NSH with a wide
range of expertise on hard materials and tissues, email NSH at
histo@nsh.org for information on how to join the committee.

I find it interesting that hoof material needs decalcification since equine
hoof is made up of extremely hard keratin and unless it is ATTACHED to
bone, acid decalcification should not be necessary. The canine claw is a
bit different, and has bone involved just before the formation of the nail.
  There has been past discussion on how to handle hoof material (nail, etc)
on Histonet and should be in Histonet archives. 

I believe Jane Chladny wrote an article for Histologic (Sakura Finetek) a
few years ago on fixation, softening and processing of hooves. Sakura
website has Histo Logic available to all.

My experience with horse hoof was extreme, HUGE slabs, embedded in PMMA
plastic, and the sections curled off the slides, even though glued down
with superglue. The tough keratin has little water in it, very dry and very
hard and very difficult to infiltrate (probably why it sections better
after a water soak with Tween, TritonX, detergents, etc) in paraffin.  In
talking to another person who did the same thing (hoof in PMMA), she had
the same curling off slide syndrome.  

I am assuming long exposure to nitric acid is actually hydrolyzing the
protein of keratin, softening it to some extent, however, that could damage
the few cells containing nuclei in the layers.  Decalcification is not
happening since there is no calcium to be removed.

Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303

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