HEfärgningen

HE-färgningen, also called hematoxylin–eosin staining or H&E, is the most widely used staining method in light microscopy to reveal tissue structure. Hematoxylin stains acidic structures (basophilic), such as nuclear DNA and RNA, yielding blue to purple nuclei; eosin stains basic structures (eosinophilic), including cytoplasm, collagen, and extracellular matrix, giving pink to red contrasts.

The technique is normally performed on formalin-fixed, paraffin-embedded tissue sections. After deparaffinization and rehydration, hematoxylin is applied to stain nuclei, often followed by differentiation and a bluing step. Eosin is then applied as a counterstain. The slides are dehydrated, cleared, and mounted for microscopic evaluation.

There are several hematoxylin formulations (for example Harris, Mayer’s, or Gill’s) and staining protocols; pH and mordant choice influence color intensity and contrast. HE staining provides a broad view of tissue architecture and is typically the first-line stain in diagnostic pathology, frequently used before or alongside immunohistochemistry.

Limitations include limited molecular specificity and reliance on morphology alone; it cannot identify particular cell types or proteins. Additional stains or molecular techniques are used when precise characterization is required. Despite limitations, HE-färgningen remains a standard reference method for assessing normal and diseased tissue, tumor margins, inflammation, and fibrosis.