What type of stain is hematoxylin categorized as?

Hematoxylin is categorized as both a differential and a regressive stain, which makes this choice accurate.

As a differential stain, hematoxylin allows for the visualization of various cellular components by binding to specific structures within cells and tissues. It primarily highlights nuclei by staining DNA and RNA, helping to distinguish between different cell types or pathological changes.

In addition, hematoxylin is considered a regressive stain because it is initially applied in a way that saturates the tissue, and then subsequent steps, such as rinsing, are employed to remove excess stain. This process allows for better visualization of cellular details by controlling the intensity of the stain in the tissue.

Therefore, hematoxylin plays a dual role, facilitating both the differential identification of structures in histological specimens and the regressive technique that enhances the clarity and quality of the staining for analysis.