Esophagus, mucosa (cross section)
In the mucosa of the esophagus --
Esophageal epithelium is non-keratinized stratified squamous.
To recognize this epithelium as non-keratinized, note the absence of a stratum granulosum (cf., the keratinized epidermis of skin), and note that cells on the lumenal surface of this epithelium appear similar to those deeper in the epithelium, with nuclei clearly present.
Esophageal lamina propria is less cellular (fewer lymphocytes) than that in the stomach and intestine, presumably because the protective stratified squamous epithelium is more effective at keeping out foreign antigens. Nevertheless, lymph nodules may occur.
Esophageal muscularis mucosa is noticably thicker than that in the stomach and intestine, but includes only longitudinal muscle fibers.
When the esophagus is cut in cross section (across its long axis, as in the micrograph above), all of the smooth muscle fibers in the muscularis mucosae will also be cut in cross section. (Hence, all the smooth muscle nuclei in the above micrograph appear small and round, rather than elongated.)
Because the longitudinal fibers occur in bundles, a longitudinal section passing between bundles may not include any evidence of muscularis mucosae.
More esophagus examples:
Comments and questions: firstname.lastname@example.org
SIUC / School
of Medicine / Anatomy / David
Last updated: 26 December 2001 / dgk