Cell population kinetics in the epithelium of the colon of the male rat.

The present study was undertaken in order to try to define some of the kinetic parameters in the colonic mucosa of normal Wistar rats. Preliminary observations showed considerable morphological differences in the mucosa from site to site along the length of the colon. In particular the height of the crypts (measured in cells) was variable. In addition labelling index studies demonstrated dramatic variations in the distribution of labelling along the length of the crypts from site to site in the bowel. A single site in the descending colon was selected for more detailed study using a stathmokinetic agent, vincristine, and the continous labelling technique with tritiated thymidine. The results of these investigations suggest that there exists at the base of the crypt a subpopulation of cells cycling more slowly than the cells in the rest of the proliferative compartment. Growth fraction appears to fall with rising cell positions within the crypt.