The Intestine as a Model for Studying Stem-Cell Behavior

Abstract

The intestine is lined by a simple columnar epithelium that folds into a number of cavities—the crypts of Lieberkuhn—embedded in the connective tissue. In the small intestine, there are also finger-like protrusions known as villi, which are covered in this epithelium. The villi are approximately ten times larger than the crypts, but much less common (4–7× fewer, depending upon the intestinal region) (1). The functional cells are located on the villus (or toward the top of the crypts of the large intestine), and are continuously sloughed off into the lumen. These cells are replaced by massive cell production within the bottom two-thirds of the crypt, where cells in the mouse are dividing approx twice daily. This crypt region is therefore frequently referred to as the proliferative zone.