Figure 1.

Derivation of cardiac-resident macrophages during embryonic and postnatal development. During embryonic development, cardiac-resident macrophages are derived from either yolk-sac macrophage-derived or fetal liver monocyte-derived cardiac-resident macrophages. The former develop, starting around embryonic day 7.0 (E7.0), and migrate to the heart at E7.5. The latter are derived from the erythroid myeloid progenitors from the hemogenic endothelium of the yolk sac (E8.0–8.5) and from the hemogenic endothelium of the aorto-gonad and mesonephros (AGM) region (E10.5). Fetal liver monocyte production starts at E12.5. Embryonic-derived cardiac-resident macrophages endure in the heart primarily by proliferation in situ. Bone marrow monocyte-derived cardiac-resident macrophages appear in the heart starting around postnatal day 14 (P14) and endure in the heart by continuous monocyte seeding from the circulation.