stainers

A stainer is a person or device involved in applying chemical dyes to biological specimens to make structures visible under a microscope. Staining enhances contrast by preferentially coloring specific cellular components or microorganisms, facilitating observation and analysis.

In histology and pathology, stains color tissue sections prepared from formalin-fixed, paraffin-embedded specimens. Common stains include hematoxylin and eosin (H&E), where hematoxylin stains nuclei blue and eosin counterstains cytoplasm and extracellular matrix pink. In microbiology, staining techniques such as the Gram stain differentiate bacteria by cell wall properties, while special stains (e.g., periodic acid–Schiff, acid-fast, silver stains) highlight particular components. The choice of stain depends on the diagnostic goal and the tissue type.

Staining procedures typically involve fixation, preparation of the specimen (such as deparaffinization for slide-mounted tissues), application of dye solutions, rinsing, and mounting for microscopic examination. Staining protocols require precise timing, temperature control, and reagent quality to avoid artifacts or over- or under-staining. Quality control includes the use of reference slides and repeated runs to ensure consistency.

Automation has led to the development of automated stainers, which program and execute staining steps to standardize results in clinical laboratories. Training and safety considerations apply to both manual and automated staining to manage chemical reagents and waste.