Histoautoradiographic investigation concerning the age-dependent proliferation kinetics of the epithelium of the rat small intestine

The aging of the cells depends on their mitotic activity, which is particularly evident in multicellular organisms. By means of histoautoradiography we studied the cell kinetics on a total of 244 Wistar rats aged 6 days, 6 weeks, 6, 12, 23 and 28 months, respectively, with these studies being centred on the mucosa of the small intestine since this mucosa is one of those tissues having the most intensive cellular metabolism. We succeeded in demonstrating that the regeneration rate of cells per hour in the crypts of the small intestine and the migration speed of the enterocytes differ in young and old individuals and that the intermitotic cells have age-dependent properties as well. Moreover the intermitotic cells revealed a non-growth fraction which, at an advanced age, decreases only a little, although significantly in terms of statistics. For the easily vulnerable crypt epithelium it proved to be a reserve capacity and can be included in the proliferating pool, if necessary. (author)