Renewal of the epithelium in the descending colon of the mouse. II. Renewal of argentaffin cells

Argentaffin cells (defined as containing groups of fine, iron hematoxylin stained granules) were examined in the epithelium of the descending colon of the mouse at various times after the initiation of a continuous infusion of 3 H‐thymidine, using radioautography of semithin Epon embedded sections. These argentaffin cells do not show mitosis nor do they take up label one hour after injection of 3 H‐thymidine. Therefore, they do not have the capacity to divide. Nevertheless. by two days and later after the beginning of continuous infusion of 3 H‐thymidine, labeled argentaffin cells are present. It is, therefore, concluded that argentaffin cells arise from unidentified precursor cells containing no iron hematoxylin stained granules (or too few for identification with the light microscope). The number of labeled argentaffin cells increases during the first few days after continuous infusion of 3 H‐thymidine, while they migrate upward along the crypt wall, somewhat more slowly than vacuolated‐columnar and mucous cells do. The results demonstrate that at least some of the argentaffin cells undergo migration and renewal in the colonic epithelium.