This specimen was stained with periodic acid-Schiff (PAS) stain to chemically convert the sugars in mucus into a magenta-colored product. It was counter-stained with hematoxylin to show additional details.
This allows the identification of the surface mucous cells as they extend down into gastric pits. It also makes it easy to see the mucous neck cells.
Gastric Pits - surface mucous cells invaginate to form gastric pits. Their mucus is intensely stained a dark magenta.