What Is Histology
This table gives some examples of basic and acidic dyes used in staining.
For basic dyes, the reaction of the anionic groups of cells (these include the phosphate groups of nucleic acids, sulphate groups of glycosoaminoglycans, and carboxyl groups of proteins) depends on the pH at which they are used.
For acidic dyes, the dye in question can often in addition be selective for particular acidophilic components. a technique called the Mallory staining technique uses three acidic dyes: aniline blue, acid fuschin and orange G, which selectively stain collagen, cytoplasm and red blood cells respectively.
Periodic acid Schiff reaction (PAS)
The Schiff reagent is a bleached basic fuschin that reacts with aldehyde groups. This reaction results in a deep red colour in the section. It is the basis of the PAS stain.
PAS stains carbohydrates and carbohydrate rich macromolecules a deep red colour (magenta). A light microscope, equipped with fluorescence, is used to visualise the staining. The fluorescent antibodies are excited at one wavelength of light, and they then emit light at a different wavelength. Using the right combination of filters, the staining pattern produced by the emitted fluorescent light can be observed. For example, this photo shows some cells that have been immunofluorescently stained for the protein actin.