Haematoxylin and Eosin (H & E) is one of the most widely used histological staining methods of all and is a primary contrast method in medical diagnosis of biopsy specimens. Properly administered, the H & E stain can yield a suprising amount of useful information. Though H & E stains were first implemented at least a century ago, the generalized method is still considered essential for recognition of tissue types and for recognizing morphological indicators diagnostic of cancer pathology. H & E staining has been in use relatively unchanged for many years, the approach has evolved to include a variety of specialized, though related, protocol chemistries for different tissues and contrast emphasis. H & E staining is remarkably robust and works well with a variety of fixatives and is used to discriminate between a broad range of cytoplasmic, nuclear and extracellular matrix features.
The H & E staining method involves application of haematoxylin, a basic dye, to yield a blue-purple contrast on basophilic structures. An acidic eosin counterstains eosinophilic structures bright pink. Various hues can also be present in the sample, including yellow and brown due to intrinsic pigments such as melanin. Hydrophobic structures remain clear; such structures include adipocytes, myelin around neuronal axons, and Golgi membranes.