Which statement correctly describes a monocyte, the blood cell that differentiates into a macrophage in tissues?

Which statement correctly describes a monocyte, the blood cell that differentiates into a macrophage in tissues?

• A. It Becomes a Macrophage When It Leaves the Blood Circulation
• B. This Cell Is a Granulocyte
• C. This Cell Comprises the Majority of Agranulocytes
• D. It Carries Oxygenated Blood

Answer: (A)

Monocytes circulate in the bloodstream and, upon migrating into tissues, differentiate into macrophages. This tissue transition is what makes the statement correct: these cells are designed to move from blood into tissues where they become highly phagocytic macrophages that also present antigens to help activate other immune cells. This distinguishes them from granulocytes (which have visible granules) and from red blood cells (which carry oxygen) or from lymphocytes (the other major group of agranulocytes).

Monocytes circulate in the bloodstream and, upon migrating into tissues, differentiate into macrophages. This tissue transition is what makes the statement correct: these cells are designed to move from blood into tissues where they become highly phagocytic macrophages that also present antigens to help activate other immune cells. This distinguishes them from granulocytes (which have visible granules) and from red blood cells (which carry oxygen) or from lymphocytes (the other major group of agranulocytes).