Organ size is limited by the number of embryonic progenitor cells in the pancreas but not the liver

• Published in: Nature Vol. 445; no. 7130; pp. 886 - 891
• Main Authors: Stanger, Ben Z., Tanaka, Akemi J., Melton, Douglas A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.02.2007; Nature Publishing; Nature Publishing Group
• Subjects: Animals; Apoptosis; Biological and medical sciences; Blastocyst - metabolism; Blood; Cell Count; Cell Death; Cell growth; Cellular biology; Central nervous system; Compensation; Embryology: invertebrates and vertebrates. Teratology; Embryonic Stem Cells - cytology; Female; Fundamental and applied biological sciences. Psychology; Growth factors; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humanities and Social Sciences; Liver; Liver - anatomy & histology; Liver - cytology; Liver - embryology; Male; Mice; Molecular biology; multidisciplinary; Organ Size; Organogenesis. Fetal development; Organogenesis. Physiological fonctions; Pancreas; Pancreas - anatomy & histology; Pancreas - cytology; Pancreas - embryology; Physical growth; Rodents; Science; Science (multidisciplinary); Size; Trans-Activators - deficiency; Trans-Activators - genetics; Trans-Activators - metabolism; Vertebrates; Vertebrata; Embryo; Mammalia; Mouse; Size; Rodentia; Development; Morphometry; Pancreas; Progenitor cell; Organ
• DOI: 10.1038/nature05537
• ISSN: 0028-0836; 1476-4687

The determinants of vertebrate organ size are poorly understood, but the process is thought to depend heavily on growth factors and other environmental cues. In the blood and central nervous system, for example, organ mass is determined primarily by growth-factor-regulated cell proliferation and apoptosis to achieve a final target size. Here, we report that the size of the mouse pancreas is constrained by an intrinsic programme established early in development, one that is essentially not subject to growth compensation. Specifically, final pancreas size is limited by the size of the progenitor cell pool that is set aside in the developing pancreatic bud. By contrast, the size of the liver is not constrained by reductions in the progenitor cell pool. These findings show that progenitor cell number, independently of regulation by growth factors, can be a key determinant of organ size. One size fits all For many organs, including blood, liver and muscle, tissue or organ size can be adjusted for cell loss. But not for the pancreas. New work shows that pancreas size is fixed by the number of progenitors set aside during embryogenesis. Other organs such as lung, kidney and thymus may be similarly size-limited, and this may relate to an organ's capacity for regeneration.