<prompt> Macrophage is -MonocytesEosinophilsNeutrophilsLymphocytes  <response>: Ans. is ai.e., Monocytes o The monocytes migrate to tissues and become part of the tissue fixed macrophages.o Blood macrophages - Monocyteso Tissue macrophages - HistiocytesTissue macrophages histiocytes in different tissue are mentioned below -o Lung: Alveolar macrophages or Dust cellso Placenta: Hoffbauer cellso Brain: Microgliao Kidney : Mesangial cellso Liver : Kupffer cellso Spleen : Littoral cellso Bone: Osteoclastso Synovium: Type-A lining cellso Skin: Langerhans cellso Spleen: Red pulp sinusoidal lining cellso Connective tissue: Histiocytes tissue macrophageso Life span of monocytes in circulation is 1-3 days whereas tissue macrophages have life span of 3 months to years 