Mayer's hematoxylin is an alum hematoxylin. It is a commonly used nuclear stain that may be employed for both progressive and regressive staining methods(discussed in further detail later in this course). It is often used as a nuclear counterstain for special stains and immunohistochemistry. For these applications, Mayer's is used to stain the nuclei and then blued without the use of a differentiating solution. Mayer's is considered a water-based stain as it does not contain any alcohol.
