Dynamic features of duct epithelial cells in the mouse pancreas as shown by radioautography following continuous ³H‐thymidine infusion

Abstract

The possibility of turnover of the epithelial duct cells was examined in the adult mouse pancreas by radioautography following continuous administration of 3H-thymidine for periods varying from 1 h to 60 days. One hour after an injection of 3H-thymidine, the label observed in small and large ducts was low but increased with the duration of the continuous infusion of 3H-thymidine and reached a level of about 67% cells labeled after 60 days. The rate of duct cell labeling was estimated from the regression line of the labeling index vs. time in four types of ducts classified according to their inner diameter and the presence of the adventitia and was given as 0.60% cells per day in small (adventitia-free) ducts (phi 4-12 micron), 0.89%, 1.02%, and 1.23% cells per day in large (adventitia-including) ducts (phi 15-29, 30-49, and 50-160 micron respectively). In contrast, the labeling index of aciner cells after a 60-day infusion indicated an addition of only 0.02-0.07% per day, and that of islet cells 0.14-0.22% per day. It is known that most parenchymal cells belong to either expanding or renewing cell populations. The acinar cells of the pancreas have been shown to constitute an expanding population, a conclusion confirmed by the low addition of cells observed in the present work. However, the relatively high rate of cell addition in the duct epithelia indicates that they may turn over in a period of 2.7 months in the case of large ducts and 5.6 months in the case of small ducts.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation of Islet β-Cell Proliferation by Prolactin in Rat Islets

“…Curiously, the exocrine pancreas does contain large homogeneous regions suggesting that its development and growth follows a different pattern than the endocrine pancreas (46). In addition, the failure to observe clusters of labeled cells within islets after infusion in vivo with [ 3 H]thymidine for 60 days does not support the existence of a limited pool of p-cells with a higher growth potential (47). Moreover, it has been reported that only 0.5-4.0% of all p-cells in adult mice are in a senescence pathway in which they express tyrosine hydroxylase and are no longer capable of dividing (19).…”

β-Cell Growth: An Unusual Paradigm of Organogenesis That is Cyclin D2/cdk4 Dependent

“…20 In contrast, tritiated thymidine experiments in old mice suggested that β-cell turnover could be as little as 0.2% per day. [21][22][23][24] In the process of studying β-cell growth we were struck by the lack of β-cell proliferation in 3-month-old wild type control mice, which were brdu positive only ~0.2% following a 6 hour label. We speculated that variable estimates of β-cell turnover could be due to developmental dynamics: β-cell proliferation from islet growth is difficult to differentiate from β-cell turnover, as β-cell mass expands enormously over the first year of life in young rodents.…”

Turnover of Acinar and Islet Cells in the Pancreas of Monosodium Glutamate‐Treated Obese Mice

“…This makes it difficult to examine the cell renewal in pancreatic tissue. Therefore, it has not been fully analyzed (21)(22)(23)(24). Cameron reported that the estimated turnover time of acinar and islet cells in mice was 520 and 250 days, respectively (21).…”

“…Cameron reported that the estimated turnover time of acinar and islet cells in mice was 520 and 250 days, respectively (21). Tsubouchi et al (22,23) estimated turnover time of acinar and islet cells in mice as 2564 days and 500 days, respectively. Little is known about cell turnover of pancreatic cells in hypothalamic obesity.…”