FIGURE 17.6 • Photomicrograph of esophagogastric junction. This low-magnification photomicrograph shows the junction between the esophagus and stomach. At the esophagogastric junction, the stratified squamous epithelium of the esophagus ends abruptly, and the simple columnar epithelium of the stomach mucosa begins. The surface of the stomach contains numerous and relatively deep depressions called gastric pits that are formed by the surface epithelium. The glands in the vicinity of the esophagus, the cardiac glands, extend from the bottom of these pits. The fundic (gastric) glands similarly arise at the base of the gastric pits and are evident in the remaining part of the mucosa. Note the relatively thick muscularis externa. 40.
FIGURE 17.7 • Mucosal surface of the stomach. a. Scanning electron micrograph showing the mucosal surface of the stomach. The gastric pits contain secretory material, mostly mucus (arrows). The surface mucus has been washed away to reveal the surface mucous cells. 1,000. b. Higher magnification showing the apical surface of the surface mucous cells that line the stomach and gastric pits. Note the elongate polygonal shape of the cells. 3,000.
FIGURE 17.8 • Gastric glands. a. This photomicrograph shows the fundic mucosa from an Alcian blue/PAS preparation to visualize mucus. Note that the surface epithelium invaginates to form the gastric pits. The surface mucous cells and the cells lining the gastric pits are readily identified in this preparation because the neutral mucus within these cells is stained intensely. One of the gastric pits and its associated fundic gland are depicted by the dashed lines. This gland represents a simple branched tubular gland (arrows indicate the branching pattern). It extends from the bottom of the gastric pit to the muscularis mucosae. Note the segments of the gland: the short isthmus, the site of cell divisions; the relatively long neck; and a shorter and wider fundus. The mucous secretion of mucous neck cells is different from that produced by the surface mucous cells as evidenced by the lighter magenta staining in this region of the gland. 320. b. Schematic diagram of a gastric gland, illustrating the relationship of the gland to the gastric pit. Note that the isthmus region contains dividing cells and undifferentiated cells; the neck region contains mucous neck cells, parietal cells, and enteroendocrine cells, including amine precursor uptake and decarboxylation (APUD) cells. Parietal cells are large, pear-shaped acidophilic cells found throughout the gland. The fundus of the gland contains mainly chief cells, some parietal cells, and several types of enteroendocrine cells.
most of the volume of the cell. It typically appears empty in routine hematoxylin and eosin (H&E) sections because the mucinogen is lost in fixation and dehydration. When the mucinogen is preserved by appropriate fixation, however, the granules stain intensely with toluidine blue and with the periodic acid–Schiff (PAS) procedure. The toluidine blue staining reflects the presence of many strongly anionic groups in the glycoprotein of the mucin, among which is bicarbonate.
The nucleus and Golgi apparatus of the surface mucous cells are located below the mucous cup. The basal part of the cell contains small amounts of rough endoplasmic reticulum (rER) that may impart a light basophilia to the cytoplasm when observed in well-preserved specimens.