[Origin of the phagocytes of the central nervous system]

Presence of cells having hemopoietic origin in an intact tissue and in the lesion focus in the brain of xenogenic (a rat and mice) radiative chimeras has been studied in order to elucidate the sources of phagocytes in the CNS and their relation to the microglial elements. To identify the cells of the hemopoietic origin in the xenogenic radiative chimeras, an indirect immunofluorescent method has been applied using a specific antiserum against nonsoluble antigens of the rat bone marrow cells. In the intact cerebral tissue of the xenogenic radiative chimeras no cells of the donor type have been revealed during one year after irradiation and bone marrow transplantation. The cells having hemopoietic origin (macrophages, leucocytes) are revealed in the lesion locus (inflammatory granuloma) and in the surrounding cerebral tissue. A suggestion is made that phagocytes in the CNS lesion focus are of hematogenic origin and that there is not any histogenic connection between the microglia and the system of mononuclear phagocytes.