How does histochemistry identify the locations of molecules and enzymes in cells?

In the context of morphology, histochemistry identifies the location of molecules and enzymes within cells by utilizing differential staining and chemical reactions to visualize specific constituents in situ.12

Identifying Molecules

Histochemists use specific dyes that bind to particular structural and molecular components, reflecting the chemical differences of those constituents. By selecting appropriate dyes, researchers can identify the presence and location of substances such as glycogen, DNA, RNA, and proteins.1

Identifying Enzymes

To locate specific enzymes within a thin slice of tissue, histochemists employ a multi-step process:
* Substrate Reaction: The tissue is provided with a specific substance upon which the target enzyme acts, producing a reaction product.1
* Precipitation: A secondary compound is added that reacts with that product to form an insoluble, colored compound.12
* Visualization: Because this colored precipitate is insoluble, it remains at the site of the enzymatic activity, making the enzyme's location relatively easy to identify under a microscope.12