The role of reticulo-endothelial cells in hemopoiesis in the adult liver.

Form their sinusoidal position in the properly stimulated adult liver, the reticulo-endothelial cell invades the hepatic cords. Here, their cytoplasmic processes come in direct contact with the cytoplasm of the hepatic cells. Ferritin is transferred from cord cells to the reticulo-endothelial cell, initiating extravascular hemopoiesis. As the reticulo-endothelial cell regains an intravascular position, it takes on the characteristics of a proerythroblast. The activity described for the adult liver follows the pattern observed in the fetal liver where proerythroblasts appear within the hepatic sinusoids only after hemopoiesis is established in the adjacent extravascular hepatic cords.