Gastric Histology
| Overview |
|---|
- The stomach possesses all of the basic histological layers of the GI Tract (See: GI Tract Histology). Different anatomic regions of the gastric mucosa possess specialized glands, thus giving unique histological features to different areas of the stomach. Briefly, the gastric body and fundus possess glands designed for secretion of a highly acidic and proteolytic gastric juice, while the gastric antrum possess glands designed for secretion of the endocrine hormone gastrin as well as large amounts of mucus.
| Basic Layers |
|---|
- Gastric Mucosa
- Gastric Epithelium: Throughout the stomach, the areas of the gastric epithelium which face the lumen of the stomach produce substantial amounts of mucus which covers the gastric wall and offers protection from the digestive gastric juice. The gastric epithelium also forms large invaginations into the Lamina Propria, creating gastric glands which are described in the next section.
- Gastric Lamina Propria: Is a fairly wide layer which accommodates the rather lengthy gastric glands and contains some lymphoid aggregates of MALT
- Gastric Muscularis Mucosa: Is a thin layer of smooth muscle cells which forms the border past which gastric glands do not extend.
- Gastric Submucosa:
- Is a relatively loose collagenous layer which conducts larger blood vessels.
- Gastric Muscularis Propria:
- The gastric muscularis propria, in addition to posessing an inner circular muscle layer and an outer longitudinal muscular layer common to all GI tract segments, also possesses an innermost muscle layer with an oblique geometry.
- Gastric Adventitia
- The adventitia of the stomach is composed solely of a layer of serosa which forms the gastric surface of the peritoneum.
| Gastric Glands |
|---|
- Overview
- The stomach possess two histological subtypes of glands which served different functional purposes. As mentioned, the gastric glands are formed by invaginations of the gastric epithelium which dive into the lamina propria and are bounded by the thin layer of muscularis mucosa.
- Oxyntic Glands
- Oxyntic Glands are largely present in the gastric body and fundus and are formed by deep, straight invaginations of the gastric epithelium which can be observed on the luminal surface of the stomach as "Gastric Pits". The neck of oxyntic glands is populated with mucous secreting cells similar to those on the lumial surface of the stomach. Along the middle of the glands lie parietal cells which secrete stomach acid as well as Intrinsic Factor important for Vitamin B12 transport. Enterochromaffin Cells can sometimes be observed lying directly adjacent to Parietal Cells and are a critical convergence point for the coordinated regulation of Stomach Acid Secretion.Toward the base of oxyntic glands lie gastric chief cells which produce pepsinogen, a zymogen that is converted into potent protease pepsin within the gastric lumen.
- Pyloric Glands
- Pyloric Glands are largely present in the gastric antrum and are formed by deep, branched invaginations of the gastric epithelium. The majority of the pyloric gland epithelium is made up of mucous secreting cells which secrete enormous amounts of mucous which help protect the duodenum from stomach acid following emptying of the stomach. Scattered throughout the pyloric glands are G Cells which secrete gastrin, an endocrine hormone that is involved in regulation of Stomach Acid Secretion.