[Mononuclear phagocyte system. Morphology and function of the principal constituting cells]

Histo-monocytes are cells playing an important role in host defense reaction and purification of the organism. These cells belong to a new system of highly phagocytic mononuclear cells termed "mononuclear phagocyte system". This system includes the promonocytes and their precursors in the bone marrow, the monocytes in the peripheral blood and the different types of histiocytes and macrophages particularly Kupffer cells. Histiocytes can also transform into epithelioid cells and giant cells. The inclusion of all these cells in this system is based on similarities in the morphology, function, origin and kinetics of the phagocytes. The most important morphologic characteristics of these cells are described. It is also shown that the mononuclear phagocytic system is a secretory system. The different types of products are described. Recently, so-called accessory cells of the immunity were described, comprising dendritic reticular cells from the follicles and interdigitating reticular cells from the deep cortical zone of the lymph node. Those cells belong both probably to the system. The cells of this system are engaged in the clearance of multiple organs, in the inflammatory process, in the immune response and in the immune surveillance against tumor.