Plate 10.199 Jejunum: Cross Section

Ronald A. Bergman, Ph.D., Adel K. Afifi, M.D., Paul M. Heidger, Jr., Ph.D.
Peer Review Status: Externally Peer Reviewed

A, Low magnification plate of a cross section of the jejunum. Note the prominent finger-like villi projecting into the lumen and the darker intestinal glands beneath them. The prominent muscularis is seen outside the intestinal glands.

B, Higher magnification, showing some details of the structure of the jejunal wall. Each villus is covered by simple columnar epithelium; the connective tissue composing its core also fills spaces between intestinal glands. Note that the epithelium covering the villi continues into the intestinal glands. New cells are formed in the depth of these glands and migrate upward to the surface of the villi.

Note the plexus of Meissner in the submucosa and the myenteric plexus of Auerbach between the two layers of the muscularis. These plexuses contain autonomic ganglia that receive preganglionic parasympathetic fibers from the vagus nerve and sacral outflow. Postganglionic fibers pass to the muscles and vessels of the gut wall and stimulate muscular contraction and intestinal secretion. The two layers of the muscularis (inner circular and outer longitudinal) are well defined. The serosa is a connective tissue sheath on the outside of the intestinal wall, covered by mesothelial cells.

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