<prompt> Macrophage is-MonocytesEosinophilsNeutrophilsLymphocytes  <response>: The monocytes migrate to tissues and become part of the tissue fixed macrophages.Blood macrophages MonocytesTissue macrophages Histiocytes Tissue macrophages histiocytes in different tissue are mentioned below Lung: Alveolar macrophages or Dust cellsPlacenta: Hoffbauer cellsBrain: MicrogliaKidney: Mesangial cellsLiver: Kupffer cellsSpleen: Littoral cellsBone: OsteoclastsSynovium: Type-A lining cellsSkin: Langerhans cellsSpleen: Red pulp sinusoidal lining cellsConnective tissue: Histiocytes tissue macrophagesLifespan of monocytes in circulation is 1-3 days whereas tissue macrophages have life span of 3 months to years 