There are tons of histological stains with different functions which visualise different aspects of tissues. The standard and most common stain used in practise is H&E. The H stands for haematoxylin whereas E stands for eosin.
Haematoxylin = stains the nuclear components purple (Basic)
Eosin = stains the cytoplasm pink (Acid)
The difference in PH determines which part of the cell the stains, stain. For example, because haematoxylin is basic it is positively chartered which reacts with the negative charged components of the nucleus. Conversely, eosin is acidic which makes it negatively charged this reacts which the positively charged proteins the cytoplasm of the cells. This stain is the bread and butter of histology and understanding it is essential. It can be used to identify different tissue types and structural diseases such as cancer.
Periodic acid-Schiff staining
This stain is used to identify polysaccharides such as glycogen, glycoproteins and glycolipids. Glycogen granules can be used to visualise bladder, kidney, ovary and pancreas tumours. This stain can be used in conjunction with diastase. Diastase is an enzyme which destroys glycogen and therefore, does not stain for it. When these two are used together it can be used to identify glycogen.
Alcian blue staining
This stain is used to visualise mucins. It must be used at PH 2.5 and stains mucins inside goblet cells. Therefore, this stain can be used as show Barretts oesophagus. This is when epithelium changes in the oesophagus from the normal stratified squamous epithelium to columnar epithelium lined with specialised cells. This condition is relatively common and is changed by an environmental change such as acid reflux which can be caused by prolonged periods of smoking. The change of epithelial tissue type is known as metaplasia.