Basic guide to histological staining
Dr A McLeod

Stains are used to enhance the preparation and make selected elements easier to distinguish. Choice of stain will depend on the tissue and the object of the examination.

Giemsa: a mixture of methyline blue and eosin - the appearance is unsurprisingly similar to, but not identical to the appearance under H&E and Wrights stain.

Haematoxylin and Eosin.
Haematoxylin has a deep blue-purple color and stains nucleic acids by a complex, incompletely understood reaction. It stains the cell nucleus well enough to distinguish varying cell-type- and cancer-type-specific patterns of condensation of heterochromatin (hematoxylin staining) that are diagnostically important.
Eosin is pink and stains proteins nonspecifically. It stains, cytoplasm, extracellular matrix and nuceoli.
In a typical tissue, nuclei are stained blue, whereas the cytoplasm and extracellular matrix have varying degrees of pink staining. A clear area of cytoplasm near the nucleus represents the Golgi zone.

Papanicolaou Stain
This histology stain is used mainly on cytological specimens. Cells in smear preparations can be stained with Pap staining. Gynecological smears (Pap smears), sputum, urine, cerebrospinal fluid, abdominal fluid, pleural fluid, synovial fluid, semminal fluid and fine needle aspiration samples can all be stained with a Pap stain. This staining technique involving five dyes in three solutions.
Periodic Acid-Schiff (PAS): This histology stain is particularly useful for staining glycogen and other carbohydrates, but is useful for many things. It is often used to show glomeruli, basement membranes, and glycogen in the liver. PAS stains glycogen, mucin, mucoprotein, and glycoproteins magenta. The nuclei will stain blue. Collagen will stain pink.

Vital stains:
Stains applied to living tissue. Divided into supravital (introduced to living tissue that has been removed from the body, but before cessation of the chemical life of the cells) and intravital (absorbed by living cells after injection into the body) stains.

Wright's stain:
Methylene blue (blue dye) has a positive charge and stains acidic granules as well as RNA and DNA all of which have negative charges; Eosin (a red dye) has a negative charge and so stains some granules and hemoglobin which are basic with positive charges, a red colour.


Updated March 2010


H&E Staining
Other stains