What do monocytes do after leaving capillaries and entering tissues?

What do monocytes do after leaving capillaries and entering tissues?

• A. Engulf platelets
• B. Promote vasoconstriction
• C. Produce histamine
• D. Convert to macrophages and perform phagocytosis

Answer: (D)

When monocytes leave capillaries and enter tissues, they differentiate into macrophages and take on the role of professional phagocytes. In this form, they actively engulf and digest microbes, dead cells, and debris, helping to clear infections. They also act as antigen-presenting cells, helping to activate the adaptive immune response by presenting processed pieces of the digested material to T cells. The other options don’t fit this role: histamine production is a function of mast cells and basophils, vasoconstriction is mediated by other factors and cell types, and while macrophages can clear various material, the typical immediate action after tissue entry is phagocytosis by macrophages.

When monocytes leave capillaries and enter tissues, they differentiate into macrophages and take on the role of professional phagocytes. In this form, they actively engulf and digest microbes, dead cells, and debris, helping to clear infections. They also act as antigen-presenting cells, helping to activate the adaptive immune response by presenting processed pieces of the digested material to T cells. The other options don’t fit this role: histamine production is a function of mast cells and basophils, vasoconstriction is mediated by other factors and cell types, and while macrophages can clear various material, the typical immediate action after tissue entry is phagocytosis by macrophages.