[Histonet] paraffin sectioning possibly calcified heart valves

[Jennifer Connell]

Hello, 
I am having trouble with sectioning of paraffin embedded human aortic valve samples. 
I received the embedded samples from a collaborator who had the embedding done by the pathology department at her institution. 

Six of the 12 samples sectioned fine but the remaining samples are developing ribbon cuts and/or are crumbling in areas when sectioned. The suggestion that calcification is causing the issue has been raised by other members of my lab. Some of the samples do appear to have calcific nodules while others may have a small bit of calcification along the valve. The samples with what appears to be calcific nodules do feel stiff at the nodules and are not being cut flat with the rest of the sample there. If I reposition the samples to a new part of the blade, the defects (ribbons or crumbling) are still in the same place or reappear in the same place quickly. 

I use Tissue-Tek Accu-Edge disposable high-profile microtome blades on a Lieca RM 2135 microtome.

For the samples that do not have the obvious nodules - is it possible this was an embedding error and I may be able to re-embed the samples and proceed?
If calcification is the issue - is it possible to de-calcify the valves after they have already been fix, dehydrated, and embedded? Or are there any other suggestions on how I could proceed?
Any advice or suggestions would be greatly appreciated. Thanks. 
Jen
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Jennifer Petsche Connell, Ph.D.
Lab Manager and Research Scientist
Integrative Matrix Mechanics Laboratory <http://www.proteoglycan.com/>
Department of Bioengineering
Rice University