Mercury Based Fixatives
Mercurials contain mercuric chloride. Their method of tissue fixation is poorly understood. While not penetrating tissue well and causing some tissue hardness, mercurials are fast and provide excellent nuclear detail. They are commonly used to fix hematopoietic and reticuloendothelial tissues.
Alcohols, including methyl alcohol (methanol) and ethyl alcohol (ethanol), are sometimes used as fixatives. They tend not to be used routinely as they cause brittleness in tissue due to their dehydrating effect. However, they are very good for cytological smears because they act quickly and give good nuclear detail.
Oxidizing agents such as potassium permanganate, potassium dichromate, and osmium tetroxide are powerful denaturants and are therefore of limited use. Osmium tetroxide is used most commonly in electron microscopy.
Picric Acid Fixatives
Foremost among the picrate based fixatives is Bouin's solution. Its mechanism of action is unknown. Like the mercurials, they give good nuclear detail but with less brittleness of tissue.
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