Clarke Fixative

Fixatives are primarily classified into aldehyde-based, mercury-based, alcohol-based, oxidizing agent-based, and picrate salt-based fixatives. Among these, the most commonly used are formaldehyde (an aldehyde) and ethanol (an alcohol).

Clarke's fixative, also known as Clarke's solution, is a precipitating fixative. After fixation, it preserves good histological morphology for H&E staining. Its advantage is that it protects nucleic acids, but it is not suitable for fixation prior to fat staining. It is intended for short-term fixation; after fixation, tissues should be transferred to 95% ethanol.