Movement of lymphocytes in mucosal epithelium

Objective:To study the movement of lymphocytes in the mucosal epithelium. Methods: Transmission electron microscopy and histology were used to observe lymphocytes in the mucosal epithelium of intestine,uterus and trachea in pig, goat, horse and rabbit. Results:Most intraepithelial lymphocytes (IEL) were situated in the basal region of the epithelium of small intestine; a few IELs located near the free surface of the epithelium. Two types of IEL existed between the epithelium layers; about 80% IEL were at the resting state with round appearance. The compartment existed between IEL and epithelium; about 20% IEL were at the active state with irregular appearance. The majority of lymphocytes in the lamina propria beneath the epithelium were at active state, some migrated toward the epithelium through the basement membrane. The number of IEL in intestine was more than that in the uterus and trachea. The number of IEL and lymphocytes in the lamina propria of the ileum were more than that of duodenum and jejunum. The number of IEL in the intestine at active state was far more than that in the uterus and trachea. The majority of IEL in ileum were at active state. Conclusion:The IEL between the epithelium of intestine comes from the lamina propria, then migrate to the lumen by passing the epithelium.