polyblasts; mesenchymal animal cells capable of capturing and digesting bacteria, the remains of dead cells, and other foreign or toxic particles (phagocytosis).

The term “macrophage,” which was introduced by E. Metchnikoff in 1892, refers to the monocytes of the blood, the histiocytes of connective tissue, the endothelial cells of the capillaries (sinusoids) of the hematopoietic organs, the Kupfer cells of the liver, the cells of walls of the alveoli of the lungs (pulmonary macrophages), and the cells of the walls of the peritoneum (peritoneal macrophages). It has been established that the precursors of macrophages in mammals are formed in the bone marrow. The cells of the reticular tissue of the hematopoietic organs also exhibit phagocytic properties. Together with macrophages, they make up the reticuloendothelial, or macrophage, system, which has a protective function in the body.