Hematoxylin and Eosin (H&E)

The Hematoxylin is a basic dye that stains acidic
components of cells a blue color.

This characteristic is known as basophilia.

Hematoxylin stains the nuclei of cells, and the RER of
the cytoplasm.

Eosin is an acidic dye that stains the basic
components of the cells a reddish-pink color.

This characteristic is known as acidophilia.

Most of the cytoplasm of cells is stained by eosin.

Bone matrix is also stained by eosin.
Periodic acid-Schiff (PAS) staining

PAS is a widely used staining technique that stains the
neutral sugars of glycosaminoglycans a pink color.

Common components stained positively with PAS
include mucus, glycogen, muco-protein, glycoprotein,
the basal lamina, organ capsules, blood vessels, etc.
Orcein

Orcein staining is used to stain elastic fibers a dark
brown-purple color.

This is used, for example, to show the elastic
components in the walls of arteries, or in the matrix
of elastic cartilage.
Osmium tetroxide

Osmium is used to stain lipids a dark black color.

It is very useful for demonstrating the myelin of
myelinated nerves, or lipid droplets in the liver or
steroid-secreting cells.
Toluidine blue

Toluidine blue is a so-called metachromatic stain.

It is a blue stain that stains specific components of tissues
a purple color.

This change in staining color known as metachromasia.

Metachromasia is seen in the matrix of hyaline cartilage,
or in the granules of mast cells.
Impregnation

Impregnation is a staining technique in which
blocks of tissue are processed in solutions
containing metals such as silver or gold, which
attach to specific components in tissues.

The silver or gold are then further processed
(reduced) and develop into dark metallic deposits.

The stained blocks are then sectioned.

Silver impregnation is widely used to stain
neurons and to demonstrate reticular fibers.
Vital staining

Vital staining refers to the uptake of dyes by cells.

If we inject Trypan blue into experimental animals,
the dye is rapidly engulfed by specific macrophages.

We can use such vital staining to demonstrate the
Kupffer cells of the liver.
Giemsa stain

There are a variety of "Romanowsky-type" stains with
mixtures of methylene blue, azure, and eosin
compounds.

Among these are the Giemsa stain and the Wright's stain
(or Wright-Giemsa stain).

The latter is utilized to stain peripheral blood smears.
Connective tissue stains

The trichrome stain helps to identify the supporting
collagenous stroma in sections from a variety of organs.

Trichrome helps in identifying normal structures, such
as connective tissue capsules of organs, the lamina
propria of gastrointestinal tract, and the bronchovascular structures in lung.
Malory stain
Masson`s trichrome

Examples of trichrome stain:
 Malory
stain: stains collagen blue
 Masson`s
green
trichrome: stains collagen