Slide #124 (human) - methacrylate embedding.  The wall of the human stomach is much like that of other mammals.  The mucosa is thrown into folds (rugae) with submucosal connective tissue cores.  Distinguish again the chief cells and parietal cells of the tubular gastric glands.  Look closely also at the muscularis mucosae, which is unusually clear here, and notice that it consists of 3 separate layers of smooth muscle: aninner and outer longitudinal and a middle circular. (How is it possible to determine the true direction of these muscle fibers?  Clue: look at the direction in the muscularis externa.)

A point to ponder: the surface epithelium of both the stomach and intestine is normally worn off and replaced totally every few days.  Where do all the new cells come from?  Have you seen many mitoses here?

Another question: Why doesn't the stomach digest itself?