undecalcified bone fixation

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From:Gayle Callis <uvsgc@msu.oscs.montana.edu>
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Acutally, perfusion NBF fixation is superior for bone if one can do it.
Postfix in same, I am not sure alc/formalin can be used this way, but one
could post fix in that. 

Use NBF, fix TOTALLY or suffer the consequences of lousy bone sections
later, change after a day, rat femurs/knees/tibias can take a week to 10
days for total fixation.
Rinse briefly, store in 70% ethanol

Alcoholic formalin is far superior to 70% alcohol, and can even be used for
tetracycline labelling, then store in 70%.  Alc/formalin gives far better
morphology than 70% alcohol which shrinks the begollys out of the soft
tissues, cartilage.  Same rules apply for time of fixation (total)

Anatech has an excellent alcoholic formalin for this purpose, easy and fast
to use.

70% alcohol is an older classic way of mineralize bone fixation, abandoned
here years ago when NBF and alc/formalin did a better job on morphology.
Any formalin fixed bone must be stored in 70% alcohol for long term storage
as the formalin breaks down over time to produce an acidic solution (formic
acid) and the bone decalcifies.  Bone distorts and twists out of shape with
long PMMA dehdyration/clearing/infiltration/polymerization, and I have
blocks to prove it.

Change storage 70% after bone has been in it for a short time,
refresh/correct the alcohol content, gets rid of any residual formalin. 
Gayle Callis
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717-3610
406 994-4705
406 994-4303

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