Expression of different liver cell markers during the early prenatal human development

The expression of the liver cell markers, vimentin, desmin, cytokeratins 7, 18, 19, and stem cell markers CD34 and Bcl-2 in the early stages of the human prenatal development was studied. Desmin was revealed in sinusoidal liver cells between 3.5 and 12 weeks of gestation; in mesenchymal cells of ventral mesentery and hepatoblasts it was detected at the 4-7th weeks of gestation. During the hepatic period of hemopoiesis, desmin-positive sinusoidal cells were located close to blood cells. So-called "cholangio-" cytokeratins 7 and 19 displayed different expression patterns. Cytokeratin 7 was found only in cholangiocytes, and cytokeratin 19 in hepatoblasts until 15-16 weeks of prenatal development. Mesenchymal cells of the ventral mesentery expressed cytokeratins 18 and 19 more than hepatoblasts at the 4-7th weeks of gestation. Bcl-2 was seen in the same period in most sinusoidal and mesenchymal cells of the ventral mesentery. CD34 positive cells were detected in liver sinusoids between the 4th and 9th weeks of gestation but probably they are not progenitors of hepatocytes during embryonic development. Ventral mesentery mesenchyma was negative for CD34. These results let us hypothesize that hepatocytes and cholangiocytes may arise from different embryonic sources: cholangyocytes derive only from duodenal epithelial cells, while hepatoblasts develop most likely with the participation of mesenchymal cells. © Pleiades Publishing, Ltd. 2007.