Feulgen stain chemically converts the deoxyribose in DNA into a magenta colored product. This is an example of histochemistry where chemical procedures are used to reveal biochemical characteristics of tissues in situ. This method is both qualitative (identifies the DNA) and quantitative (amount of DNA).
Most of the pancreas is composed of acinar cells. Acinar cells are polarized cells clustered around a central lumen which is the entrance to a duct (i.e., an acinus). Compare the nuclei in acinar cells those within blood vessels and other structures.
Acinar cells have circular nuclei while other cell types have nuclei with elongated shapes.
Red blood cells within the blood vessels do not have nuclei.
Pancreas (DNAse Treated)
This pancreas section was incubated with the enzyme deoxyribose (which hydrolyzes DNA) before Feulgen staining.
The nuclei of the acinar cells are unstained. This demonstrates that nuclei contain DNA and the Feulgen reaction is relatively specific for staining DNA.