Stomach
Mucosa
As you learned from your studies of slide 42, the stomach epithelium is simple
columnar. Look at the epithelium in this portion of the stomach. It is from
the Cardiac region and is mostly made up of surface mucous cells. Thus, the
epithelium is largely protective. The next slide you will examine is the FUNDIC region or
BODY. This part of the stomach contains specialized cells for digestion.
Look at slide 51. Find a portion of the MUCOSA that is sectioned so that you can
see the tubular glands. The cells lining the surface portion of the glands are
SURFACE MUCOUS CELLS. They are distinguished by their lighter staining cytoplasm.
The loose connective tissue in this area is called the LAMINA PROPRIA. Recall
that this layer is similar to that in the esophagus. However, because of the long glands
in the stomach lined by prominent cells, it may be hard to see, except just under the
surface mucous cells.
The portion of the gland lined by Surface mucous cells ends in a region called the
GASTRIC PIT (foveolae). The pit opens up into the NECK area of the gland. Find these
regions on your slide 51.
Identify the Lamina propria and the Neck region of the gland on this photograph.
 A higher
magnification is seen through the PIT. Note that the surface mucous cells sometimes
look like Goblet cells, but they are not Goblet cells. What are the differences
between Goblet cells and Surface Mucous cells in the stomach.
The neck region continues as the Body of the gland. It is distinguished by
purple MUCOUS NECK CELLS and the prominent round PARIETAL CELLS.
What do the parietal cells produce? Study an electron micrograph of a parietal cell to
learn how it is uniquely structured to perform its function.
 A higher magnification of the parietal cells shows
them in relation to the mucous neck cells.
 The base of the
gastric glands in the fundus is distinguished by CHIEF CELLS. These are basophilic
(staining purple with Hematoxylin and Eosin) and distinguished by the presence of Zymogen
granules. Like the pancreatic acinar cell, the zymogen granules contain digestive
enzyme precursors.
You can also see some of the lamina proprial underneath the chief cells (note the large
blood vessel.
Finally, this photo shows the layer of muscularis mucosa just under the lamina propria.
What types of enzymes are secreted by the Chief cells? After the enzymes are
secreted into the lumena of the glands, what activates them for use in the stomach?
Another cell type in the stomach is the enteroendocrine cell. This cell is
polarized in the opposite direction to that of the other gland cells. It lies at the
base of the glands, underneath the chief or parietal cells. Its secretory granules
face the blood vessels in the lamina propria. The following figures show the
enteroendocrine cells near either chief or parietal cells. Try to find an example in
your slide 51.
What types of hormones do the enteroendocrine cells in the stomach secrete?
The next layer after the mucosa and muscularis mucosa is the submucosa, seen as
connective tissue. It is similar to that in the esophagus. No glands are seen in the
submucosa of the stomach. The following photo illustrates these regions.
You may also see diffuse lymphoid tissue throughout the digestive tract. Below is
a photo of lymphoid tissue in the stomach.
Underneath the submucosa are three muscle layers called the MUSCULARIS EXTERNA.
The stomach has an inner oblique layer, which may be hard to see in some sections.
After this is the inner circular layer (seen cut in longitudinal section in this
photograph) and an outer longitudinal layer (seen cut in cross section).
The final region or layer is the connective tissue ADVENTITIA. It is lined by
mesothelium and is actually called the SEROSA over the stomach. Try to find all of
these layers in slide 51.
As in the case of the esophagus, the nerve supply to the stomach muscles and glands is
autonomic. Fibers extend from ganglia in the spinal cord to ganglia in the wall of the GI
tract. There, they synapse with other neurons localized in ganglia either in-between
the muscle layers (Auerbach's plexus) or in the submucosa (Meissner's plexus). Look only
for examples of Auerbach's plexus, as shown in the following photos.
Slide 52 is a section through the pyloric region of the stomach. It contains the basic
structure of the glands in the fundus, except that parietal and chief cells are replaced
by MUCOUS NECK CELLS. The following photo shows the mucosa and lamina propria
in the pylorus. Note that the Gastric PITs are deeper. The second photograph shows the muscularis
mucosa and submucosa.
Find the underlined regions on the photographs below
The following photographs show different views of the Auerbach's plexus in the pylorus.
They are easier to find because of the Masson Trichrome stain that delineates the
connective tissue (blue).
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