What is a substance used to impart color to tissue for microscopic study called?

A substance used to impart color to tissue for microscopic study is known as a stain. Stains are essential in histology and pathology because they enhance the contrast of the microscopic structures, making it easier to visualize and differentiate various components of the tissue. Specific stains can highlight different parts of the cells or extracellular matrix, providing valuable information about cellular morphology, structure, and function during examination.

Dyes can also change the color of materials, but in the context of microscopic study of tissues, the term "stain" is more commonly used to refer specifically to the substances that color tissue samples. Fixatives, in contrast, are used to preserve tissue structure and prevent decay, while reagents are substances used in chemical reactions but are not specifically aimed at coloring tissues. Thus, the terminology in histology clearly identifies stains as the agents used for imparting color in this particular context.