Integrin α6β4 in colorectal cancer

Figure 2 Organization of the renewal units of the human adult small intestine and colon. In the small intestine, the crypt-villus axis consists of stem and progenitor cells, located in the lower and middle third of the gland (G), respectively, with terminal differentiation occurring in the upper third so that all villus (V) cells are mature and functional. In the colon, the stem cells are located at the bottom of the glands (G) while the proliferative cell compartment extends to the middle. Cells in the upper half of the glands and the surface epithelium (SE) are non-proliferative and functional. Adapted from reference [5].