Bob,
You would have a much colder and less toxic system if you switched to the Gentle Jane method which uses a cup of LN2 to chill a heat extractor that is then placed on the Gentle Jane device. It drops at a controlled rate and contacts the tissue first which is uppermost on the mound of CryoGel. The tissue and the gel freezes in 10 -15 seconds at a much lower temperature (with thermal exchange)than  in the Histobath and minimizes ice crystal artifact.

See the details on our web site www.instrumedics.com

Bernice
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