[Immunohistochemical study of cell phenotypes in organ culture of the rat embryo liver].

The organ culture of the liver of a 14 day old rat embryo was used for immunohistochemical recognition of the available cell types. This culture contains the tissue explant, confluent monolayer cells and a zone of single cells (ZSC). At the start of cultivation a monolayer is formed at the expense of cells slipping down together from the explant, and later these cells were seen to migrate actively from the explant and to proliferate. ZSC is formed by cells migrating from the monolayer. Desmin-containing cells (hepatoblasts, Ito cells and myofibroblasts) migrate from the explant to the monolayer and ZSC. In the monolayer hepatoblasts lose gradually desmin and are converted into cytokeratin 18 (CK-18) expressing hepatocytes. In ZSC, hepatoblasts lose desmin, but no CK-18 synthesis occurs in them. The Ito cells (hypothetical progenitor cells) are spreading over the whole culture, and desmin expression in them does not change. The embryonal Ito cells may transform presumably into myofibrils. Myofibroblasts lie flat on the periphery of ZSC. Besides, desmin myofibroblasts express alpha-actin from smooth muscles. Expression of CK-18 in cells depends on the pattern of intercellular interactions. In the monolayer, CK-18 expression extends successively via the adjacent cells towards the explant. In hepatocytes, migrating into ZSC, CK-18 expression stops. In ZSC, CK-18 expression reappears in compact clusters of stopped cells. It supposed that during formation of close contacts in the monolayer the cells-predecessors may be differentiated into hepatocytes, whereas in the case of disturbance of intercellular connections in ZSC the cells-progenitors may be converted into myofibroblasts. However, on the reconstruction of cell contacts in motionless dense clusters the cells in ZSC are differentiated into hepatocytes.