The portions of cytoplasm that have many ribosomes stain in blue/purple by a mixture of hematoxylin and eosin. It has already been mentioned that the affinity of acidic structures for basic dyes is called basophilia and these regions of the cytoplasm are called basophilic.
A very demonstrative example of cytoplasmic basophilia can be seen in sections of the exocrine secretory cells of the pancreas, also called pancreatic acinar cells. They produce a protein-rich secretion, the pancreatic juice.
These pyramidal or pear-shaped cells are gathered in small spherical clusters called acini (singular: acinus). More details about these glands in the chapters “Glandular Epithelia” and “Pancreas”.
One acinus can be seen in the center of the image, surrounded by parts of neighbor acini. The cytoplasm at the base of the acinar cells contains many rich in RNA ribosomes. For this reason this area stains well with both hematoxylin and eosin, resulting in a purple color.
As you move the mouse or click on the figure, two exocrine cells of an acinus will appear delimited.
The basophilic portion of their cytoplasm will appear in light blue and some of the nuclei in a darker tone of blue. Nucleoli will be seen as small dark blue circles inside some of the nuclei.
The cellular region opposite to the cell basis, the apical region is filled with secretory grains that contain a high concentrations of proteins. They are preferentially stained in pink-orange by acidic dyes such as eosin. This region is therefore acidophilic (or eosinophilic) and will become pink after placing the mouse or clicking on the image.
Pancreas. Hematoxylin and eosin. Medium magnification.
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