Page 572 - Atlas of Histology with Functional Correlations

peptides, converting almost all of the proteins into smaller molecules. Pepsin

is responsible for converting the solid food material into fluid chyme. The
chief cells also produce gastric lipase for digesting lipids.

The secretory activities of the chief and parietal cells are controlled by
the autonomic nervous system and the hormone gastrin, secreted by the
enteroendocrine cells of the pyloric region of the stomach.

Enteroendocrine cells secrete various polypeptides and proteins with

hormonal activity that influences digestive tract functions. They are called
enteroendocrine cells because they produce gastric hormones and are located
in the digestive organs. The enteroendocrine cells are also called APUD

(amine precursor uptake and decarboxylation) cells because they can take
up the precursors of amines and decarboxylate them. These cells are not
confined to the gastrointestinal tract, but are also found in the respiratory
organs and other organs of the body where they are also known by different
names. However, because not all enteroendocrine cells accumulate amine

precursors, the APUD designation has now been replaced by the term diffuse
neuroendocrine system (DNES). Additional details, description, and
illustration of known enteroendocrine cells are found in Chapter 15.

FIGURE 14.15 | Pyloric Region of Stomach

In the mucosa of the pyloric region of the stomach, the gastric pits (3, 8) are
deeper than those in the body or fundus regions. The gastric pits (3, 8) extend

into the mucosa to about one half or more of its thickness. The surface of the
stomach is lined with a simple columnar mucous epithelium (1) that also
extends into and lines all the gastric pits (3, 8).

The pyloric glands (5, 9) open into the bottom of the gastric pits (3, 8), and
they are either branched or coiled tubular glands containing mucous secretions,

illustrated in both transverse (5) and longitudinal (9) sections. Similar to the
cardiac region of the stomach, one cell type is found in the epithelium of these
glands. The tall columnar cell stains lightly because of its mucigen (mucus) with

flattened or oval nuclei that are located at the base. Enteroendocrine cells are
also present in this region and can be demonstrated with a special stain.

The remaining structures in the pyloric region of the stomach are similar to
those of other regions. The lamina propria (4) contains lymphatic tissue and an
occasional lymphatic nodule (11). Located below the lymphatic nodule (11) is

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