Figure 166

Photomicrograph of esophagogastric junction. This low-magnifica-tion 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. x40.

rower regions of the stomach but poorly developed in the upper portion (see Fig. 16.5). When the stomach is fully distended, the rugae, composed of the mucosa and underlying submucosa, virtually disappear. The rugae do not alter total surface area; rather, they serve to accommodate expansion and filling of the stomach.

A view of the stomach's surface with a hand lens shows that smaller regions of the mucosa are formed by grooves or shallow trenches that divide the stomach surface into bulging irregular areas called mamillated areas. These grooves provide a slightly increased surface area for secretion.

At higher magnification, numerous openings can be observed in the mucosal surface. These are the gastric pits, or foveolae. They can be readily demonstrated with the scanning electron microscope (Fig. 16.7). The gastric glands open into the bottom of the gastric pits.

stomach esophagus cardiac glands fundic (gastric) glands muscularis externa

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