Zenker's fixative is a rapid-acting fixative for animal tissues. It is employed to prepare specimens of animal or vegetable tissues for microscopic study. It provides excellent fixation of nuclear chromatin, connective tissue fibers and some cytoplasmic features but does not preserve delicate cytoplasmic organelles such as mitochondria. Helly's fixative is preferable for traditional dye staining of mitochondria.
Zenker's fixative contains mercuric chloride ("corrosive sublimate"), potassium dichromate, sodium sulfate, water, and acetic acid. Fixatives containing mercuric chloride or potassium dichromate are toxic, making disposal as hazardous waste costly. Mercuric chloride can be replaced with the same weight of less toxic zinc chloride but the resulting "zinc-Zenker" may not give the same quality of fixation as the original mixture.
This fixative is named after Friedrich Albert von Zenker (1825–1898), a German physician and pathologist or Konrad Zenker, German histologist, who died in 1894. It is not connected with Friedrich Albert von Zenker.
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