This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Macrophage is- \nSelect and explain. \nA. Monocytes, B. Eosinophils, C. Neutrophils, D. Lymphocytes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The monocytes migrate to tissues and become part of the tissue (fixed) macrophages.\nBlood macrophages → Monocytes\nTissue macrophages → Histiocytes Tissue macrophages (histiocytes) in different tissue are mentioned below –\nLung: ‘Alveolar macrophages’ or ‘Dust’ cells\nPlacenta: Hoffbauer cells\nBrain: Microglia\nKidney: Mesangial cells\nLiver: Kupffer cells\nSpleen: Littoral cells\nBone: Osteoclasts\nSynovium: Type-A lining cells\nSkin: Langerhans cells\nSpleen: Red pulp sinusoidal lining cells\nConnective tissue: Histiocytes (tissue macrophages)\nLifespan of monocytes in circulation is 1-3 days whereas tissue macrophages have life span of 3 months to years', 'role': 'assistant'}]