Desmin expressing nonhematopoietic liver cells during rat liver development: an immunohistochemical and morphometric study.

The expression and cellular distribution of desmin, alpha-smooth muscle actin (A-SMA) and cytokeratin no. 8 (CK-8) and no. 18 (CK-18) in normal adult, neonatal and fetal rat liver were examined immunohistochemically on cryostat sections. At days 14 and 15 of gestation, nonhematopoietic cells in embryonic liver were strongly desmin-positive, and some of the cells, mainly located in the periphery, were also stained with anti-A-SMA. Desmin immunoreactivity gradually decreased from day 16 of gestation. A close association of desmin-positive cell processes with hematopoietic cells was observed during fetal and early neonatal development. From day 16 of gestation the pre-hepatocytes became desmin-negative, remained CK-8 and CK-18 positive. Desmin-expressing cells were numerous in the liver from the embryonic period to the neonatal age. However, their absolute number per unit area, as well as their number relative to hepatocytes, decreased with age. We suggest that desmin-positive cells in embryonic liver may act as stromal cells in the hepatic hematopoietic microenvironment and support hepatocyte development.