Heather

A question:  Are the bones brought to the lab already immersed in 
formalin?  If your pathologist is used to RECEIVING a bone already in 
formalin and if he or she (through blind luck rather than knowledge of bone 
fixation/decalcification/effects of acids on unfixed bone) may have had a 
partially fixed bone, although more on the exterior rather than interior of 
sample,and then sawed off a piece and plopped it into acid decalcifier.  It 
is doubtful a huge bone would be fixed throughout the whole or large 
sample.

Your eyes along can help you here.  A indication of partially fixed or 
unfixed bone is the bone interior will appear reddish to pinkish color i.e. 
bloody - meaning the bone is not fixed, and the sawn piece should be 
immersed in NBF longer i.e. overnight.  Fixed bone takes on the brownish 
gray look seen with formalin fixed tissues.  Take into consideration the 
dense calcified bone matrix will slow down crosslinking of formalin.  If 
the bone is mostly trabecular bone (mesh of open spaces filled with 
marrow), then fixation will proceed much faster since there is less bone in 
the sample.   Opening up/bisecting larger bone is always advisable upon 
receipt, to allow fixative to access interior surfaces - and there are some 
good saws out there to help you out.  MarMed, Cabelas's bench top band saw 
- both are inexpensive.

Yes, you are correct, there are no stupid questions.  Repeated questions 
are not stupid either and I love the diversity of repetitive correct 
answers on subjects that interest me.  These show how people have learned 
their technics and graciously pass on that information.


Gayle Callis HTL, HT, MT(ASCP)
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University
Bozeman MT 59717


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