An intestinal tree based on mitotic ages or numbers of divisions since birth. Each horizontal branch reflects a single crypt. Although all tissues have the same chronological ages, differences in stem cell division rates allow tissues within the same individual to have different mitotic ages. A small intestine tree has a more crypt branches (greater numbers of crypts) than a colon, but its branches may be shorter, which can possibly help explain why despite the greater physical size of the organ, small intestinal tumors are infrequent relative to colonic ones.
Kim et al. BMC Medicine 2005 3:10 doi:10.1186/1741-7015-3-10