A Histochemical Study of the Reticuloendothelial System of Human Marrow—Its Possible Transport Role

Intense alkaline adenosine tri-, di- and monophosphatase activity is present in the capillary endothelial cells and reticular cells of the bone marrow as well as about the individual marrow cells. The phosphatase activity of the granulocytic cells is weak by comparison and offers no difficulty in differentiation. Iron is confined to a similar topographic distribution. The described observations are discussed in terms of transport. It is suggested that the reticuloendothelial system of the marrow is essentially a transport system for the differentiating hematopoietic cells.