This image shows the entire stomach wall, including the mucosa of
the fundic region, the underlying submucosa (the muscularis mucosae
is present but can't be seen here), and the tunica muscularis.
The serosal covering of the stomach (the tunica serosa) is also
visible as a wispy layer of mesothelium at the very outside edge of
the tunica muscularis.
The tunica muscularis of the stomach has three layers (which are not easily distinguished at this magnification) while the intestines have only two. While the layers are usually described as being oriented longitudinally, obliquely, and circumferentially, this is really an oversimplification. The layers aren't very clearly defined and they intermingle with each other in places. The net effect of their contraction, however, is to cause the stomach to wring and twist itself about the long and short axes, so as to pulp up the ingested food and create the acid chyme, consisting of the semi-liquified food and gastric secretions.
Nervous elements in the submucosa and among the layers of the
tunica muscularis coordinate and control the contractions of these
muscles, as they do in other parts of the digestive tract.
Monkey stomach; H&E stain, 1.5 µm plastic section, 40x
