title: Regional differences in stem and transit cell proliferation and apoptosis in the terminal ileum and colon of mice after 12 Gy.
abstract: OBJECTIVE
  The intestinal epithelium has a high rate of cell turnover, which is regulated by stem cells located near the base of crypts. We aimed to investigate stem cell-dependent characteristics of cell proliferation, apoptosis, and crypt size in terminal ileum and different regions of the colon.
  
  
  METHODS
  Mice were studied under steady-state conditions and after radiation-induced stem cell apoptosis. Percentage of proliferating or apoptotic cells at a particular cell position (cp) along the crypt axis was expressed as labeling or apoptotic index.
  
  
  RESULTS
  Under steady-state conditions: crypt size was smallest in the ascending colon. In contrast to other regions of the colon, the distribution profile of proliferating cells in ascending colon showed some similarity to that in the terminal ileum. Postirradiation: apoptotic cells were prominent at the bottom of the crypt of mid- and descending colon but in the ascending colon, they were seen with similar frequency from cp 1 to 4. During regeneration, a constant proliferative capacity was seen above Paneth cells in the terminal ileum. In the ascending (but not mid- or descending) colon, the profile of proliferating cells over the first 4 days after irradiation showed a similarity to that in the terminal ileum.
  
  
  CONCLUSIONS
  Profiles of proliferating epithelial cells (under steady-state conditions and postirradiation) and apoptotic cells (postirradiation) suggest similarities in the location of stem cells in the ascending colon and terminal ileum.
authors.affiliation: Institute of Infection, Immunity & Inflammation, Queens Medical Centre, University of Nottingham, Nottingham, UK.
authors.forename: Ricardo M C
authors.initials: RM
authors.lastname: Gândara
authors.forename: Yashwant R
authors.initials: YR
authors.lastname: Mahida
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Potten
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D002465:Cell Movement / Q000502:physiology / Q000528:radiation effects; D049109:Cell Proliferation / Q000528:radiation effects*; D003106:Colon / Q000166:cytology / Q000502:physiology / Q000528:radiation effects*; D005260:Female; D007082:Ileum / Q000166:cytology / Q000502:physiology / Q000528:radiation effects*; D051379:Mice; D019879:Paneth Cells / Q000502:physiology; D011829:Radiation Dosage; D012038:Regeneration / Q000502:physiology; D013234:Stem Cells / Q000502:physiology / Q000528:radiation effects*