In the live thesis building blogxperiment I edit (digest, compile, write, rewrite, delete) my ongoing doctoral thesis in blog posts and put the parts together on thesis live. The title: The physiologic role of stem cells in tissues with different regenerative potential.
1.2. Tissues, organs with different turnover and regenerative potential
/bioenergetics data missing/
Liver
During organogenesis the hepatic endoderm epithelium invades the surrounding mesenchyme to form the liver bud and continued epithelial/mesenchymal interactions stimulate cell proliferation and morphogenesis. Consequently, the liver is largely of endodermal origin – including cells with a mesodermal origin and – and contains many different cell types: two epithelial liver cell types, the hepatocytes and bile duct cells, stellate cells (formerly called Ito cells), Kupffer cells, vascular endothelium, fibroblasts, and leukocytes (Desmet 1994). Hepatocytes are the main funtional liver cells accounting for ~70% of the cells in the liver and form the bulk of the liver weight (90%), yet only ~60% of total liver DNA is hepatocyte-derived (many of them with 2n, 4n, 8n DNA content). An adult human liver contains about 80 x10(9), hepatocytes. Hepatocytes are in a quiescent state and the turnover rate is low, 1-2 times/year[]. The remarkable regenerative potential of liver is well-known, in humans the liver almost completely regenerates in about 1 month after two-thirds (up to 75%) partial hepatectomy and this process can occur repeatedly in contrast to most other parenchymal organs, such as kidney or pancreas. In the literature the term liver or hepatic stem cells is used for precursors of the hepatocytes and the bile duct epithelial cells. On the other hand liver stem/progenitor cells can be define in different ways. Read the rest of this entry »
