Maea expression by EBs is dispensable for BM EI niche. (A) Expression pattern and recombination efficiency of Epor-Cre in BM of R26TdTomato reporter mice (n = 3). (B) RBC, hematocrit (HCT), hemoglobin (HGB), and reticulocyte assessment of steady state control and Maea^Epor-Cre mice. (C) Total BM cellularity of control and Maea^Epor-Cre mice (n = 4). (D) Macrophage and EB numbers in control and Maea^Epor-Cre BM (n = 4). (E) Quantification of in vivo EI formation in Maea^Epor-Cre and control BM (n = 4). (F) Quantification of EBs at various stages of maturation from control and Maea^Epor-Cre BM (n = 4). (G) Expression pattern and recombination efficiency of Epor-Cre in spleen EBs and total splenocytes from R26TdTomato reporter mice (n = 3). (H-J) Quantifications of spleen total cellularity (H), spleen macrophage (I), and EB (J) numbers in control and Maea^Epor-Cre mice (n = 4). Data are shown as mean plus or minus SEM. *P < .05, **P < .01 by unpaired Student t test.