Autoradiographic cytokinetics of colonic mucosal hyperplasia in mice.

The cytokinetics of a naturally occurring hyperplastic disease of the colon in mice were determined by autoradiography and compared to kinetic changes seen by others in nonneoplastic and neoplastic colonic disease. Cell cycle parameters were determined using the fraction-labeled mitosis method. Labeling index, labeling pattern, and migration rates were also evaluated. During colonic hyperplasia, there was an increase in variation of DNA synthesis times, resulting in prolongation of the S phase. There also was prolongation of the total cell cycle time and G1 phase. In addition, labeling index was increased 2-fold, the proliferative zone was extended to include the entire crypt column and surface mucosa, and the migration rate was accelerated. These findings parallel the "atypical" cytokinetics found in human and murine neoplastic and preneoplastic disorders of the colon and may be a typical proliferative response of mucosa to a variety of stimuli.