EBIs in stress erythropoiesis. Anemic stimulus induces erythrophagocytosis and production of the chemokine CCL2 by splenic RPMs, which attract monocytes into spleen. These monocytes associate with CD133⁺KIT⁺ early SEPs and undergo stepwise maturation into pre-RPMs and RPMs. Within EBIs, monocyte maturation occurs in concert with maturation of SEPs such that the majority of Ter119⁺ mature erythroblasts are associated with pre-RPMs and RPMs. Also seen within EBIs are conventional type 1 dendritic cells. RBCs, red blood cells. See Figure 7J in the article by Liao et al that begins on page 2580.