This high magnification
view of the duodenum shows the boundary between the mucosa and the submucosa.
Above the muscularis mucosae are seen the bases of the crypts of Lieberkuhn.
The bases of the crypts are lined by a simple columnar epithelium composed
of absorptive cells and Paneth cells (not obvious in this image). The glands
are surrounded by the highly cellular loose connective tissue of the lamina
propria. Beneath the
muscularis mucosae are Brunner's glands of the mucosa. A duct from the glands
can be seen crossing the muscularis mucosae in the lower left corner of the
image.
