Ccbe1^lacZ/lacZ fetal livers exhibit defective EBIs. (A-G) Native EBIs isolated from C57Bl/6 Ccbe1^lacZ/lacZ fetal livers have reduced numbers of Ter119⁺ erythroblasts adherent to F4/80⁺ macrophages compared with those from wild-type littermates. (H-T) Reconstituted EBIs reveal normal adhesion of Ccbe1^lacZ/lacZ erythroblasts to wild-type F4/80⁺ macrophages and reduced adhesion of wild-type erythroblasts to Ccbe1^lacZ/lacZ F4/80⁺ macrophages. n = 30 to 40 islands per group; error bars indicate SEM. KO, Ccbe1^lacZ/lacZ; WT, wild-type.