The parietal and chief cells can be made out here. The parietal cells are large and round in shape, and very eosinophilic. They often are binucleated, and in this image you can see a tri-nucleated one. The role of the parietal cell is to pump hydrogen ions out into the lumen of the stomach, thus acidifying the contents. It is able to do so by virtue of having enormous numbers of mitochondria (to provide the energy needed for active ion transport), and a system of extensive apical invaginations into which the ions are passed, creating localized concentration gradients that favor diffusion into the lumen.
The chief cell is not nearly so dramatic, though it's equally
important. Chief cells are shoved in among the parietal cells
in groups of two or three. They make enzymes and are
characterized by large amounts of RER, accounting for their
basophilic staining with H&E. The enzymes are released in
an inactive form; the acidic environment of the stomach hydrolyzes a
fragment from the precursors, converting them to active enzymes.
Lab Exercise List