Mayer's hematoxylin is an alum hematoxylin, a commonly used stain that may be employed for both progressive and regressive stains. 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 differentiator. Mayer's is also a water-based stain.
