Self-renewing resident arterial macrophages arise from embryonic CX3CR1 + precursors and circulating monocytes immediately after birth

Macrophages densely populate the arterial wall, yet their origin and homeostasis are poorly understood. Robbins and colleagues show that arterial macrophages arise from CX3CR1 + embryonic precursors and adult bone marrow–derived monocytes that colonize the tissue immediately after birth.