Mercuric chloride-based fixatives

NOTE Formalin does not preserve tissue proteins by coagulation but it is thought to form cross links with basic amino acids. Ethanol and mercuric chloride-based fixatives are based on coagulation. With few exceptions retrieval should not be performed on ethanol fixed tissues. It should only be conducted with limited controlled protocols in mercuric-chloride-based fixatives. 

One should avoid the use of highly cross-linking fixatives, such as mercuric chloride, glutaraldehyde, modified formalin, and picric-acid-based fixatives. These extensively cross-linking fixatives render the tissue virtually impermeable to the RT-PCR reaction components and to the probe. 

European museums, particularly in herbaria. The use of arsenic and mercury compounds in natural history technology and taxidermy has actually been actively encouraged over the past century with the inclusion of countless recipes for fixatives based on mercuric chloride, arsenious oxide and other compounds. 

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