This image shows the mucosa of a section of fundic stomach.  The outermost portion of the mucosa is the muscularis mucosae,  a thin (but complete) layer of smooth muscle cells that includes both circular and longitudinal fibers.  The surface of the mucosa lining the stomach is comprised of mucus-secreting simple columnar epithelial cells. This epithelium extends (invaginates) down into the lamina propria to form the gastric pits which then lead into the gastric glands.