Stomach histology

The stomach is an expanded portion of the gastrointestinal tract or GI tract that partially digests food by breaking it down mechanically and chemically in order to form a pulpy acidic fluid called chyme.

The stomach is divided into 4 anatomical regions: the cardia, fundus, body, and pylorus.

But the stomach is only divided into 3 histological regions: the cardia, fundus, and pylorus.

That’s because the fundus and body are histologically identical, so both regions are called the fundus when referring to their histology.

The cardia is a small area surrounding the opening to the esophagus which contains cardiac glands that secrete mucus.

The fundus is the largest region histologically, since it also includes the body of the stomach as well.

This region of the stomach has fundic or gastric glands that secrete digestive enzymes such as pepsin, and a protective layer of mucus.

The pylorus is the most distal region of the stomach before reaching the pyloric sphincter.

This region will have a combination of pyloric glands that secrete mucus and neuroendocrine cells that secrete gastrin.

Similar to the rest of the GI tract, the wall of the stomach has 4 main layers: the inner mucosa, submucosa, muscularis propria, and outer serosa; although some portions of the GI tract have an outer layer of adventitia instead of serosa.

This low power longitudinal section of the stomach was taken from the cardia of the stomach.

Now, if we take a closer look at the mucosa of the cardia, we can see that the surface of the mucosa has a simple columnar epithelium with many invaginations that form millions of gastric pits.

The gastric pits will comprise about a quarter of the mucosa’s thickness.

At the base of these pits, they join with multiple tubular cardiac glands that secrete mucus that protects the esophagus from gastric reflux and is also a part of the stomach’s gastric juice.

The cardiac glands extend all the way to its underlying layer called the muscularis mucosa, which is a thin layer of smooth muscle that is still a part of the mucosal layer.

The next main layer of the cardia is the submucosa, which consists mostly of dense irregular connective tissue, but also contains larger blood vessels like the ones we can see in this image.

On the right of this image we can see a portion of the overlying mucosa and on the left is a portion of the next main layer called the muscularis propria.