MITOTIC ACTIVITY AND RENEWAL RATE OF THE EPITHELIAL CELLS OF HUMAN DUODENUM

Abstract

It has previously been shown that the cells lining the duodenum of the rat are renewed every 1.6 days, those of the cat every 2.3 days. The present investigation was carried out to ascertain the mitotic activity of human duodenal epithelium by estimating the percentage of the epithelial cells which undergo division at any moment. At least 2000 cells were counted in each of the duodental tissues removed by surgery from 47 male and 9 female patients. On the average 2.7% (range 2.0 to 3.6%) of the total number of epithelial nuclei were found to be in mitosis at any instant of time. This figure is closer to that established for the rat (3.07%) than for the cat (0.8%). Most of the mitotic figures were present in the crypts of Lieberkiihn. Also cell estrusion zones were observed on many villous tips, from which epithelial cells desquamate into the intestinal lumen. Because the cell population of the duodenal epithelium in the adult is stationary, the amount of cell loss presumably is balanced by the amount of cell production. The duration of cell division of human duodenal cells is unknown. However, assuming it to be within the range of that of the rat or the cat, it can be calculated that the whole epithelial lining of the human duodenum is completely renewed once about every 2 days.