In the early development of atherosclerosis, which cell type is prominently involved in forming the fatty streak?

• A. Endothelial cell
• B. Platelet
• C. Macrophage
• D. Smooth muscle cell

Answer: (C)

In the early stages of atherosclerosis, monocytes migrate into the intima and differentiate into macrophages, which then take up modified LDL (especially oxidized LDL) through scavenger receptors. This uptake turns the macrophages into lipid-filled foam cells, and the accumulation of these foam cells creates the fatty streak—the first visible lesion of atheroma. Endothelial cells set the stage by becoming leaky and expressing adhesion molecules to recruit immune cells, but they are not the main cell type forming the fatty streak. Platelets contribute more to thrombosis and progression, while smooth muscle cells later migrate into the intima and help form the fibrous cap, not the initial fatty streak.