Cx3cr1 deficiency leads to the reduction of hematopoietic progenitors in E10.5 HBA, but not in E11.5 HBA. (A) Representative flow cytometric data and gated areas showing percentages of CD45⁺ HCs, cKit⁺CD41^low HPCs, GFP⁺CD45⁺ cells, and GFP⁺CD45⁺CD11b⁺F4/80⁺ macrophages in the HBA of Cx3cr1^+/+ (WT), Cx3cr1^+/GFP (HT, heterozygous mutants), and Cx3cr1^GFP/GFP (KO, knockout) E10.5 littermates. The percentage of CD45⁺CD11b⁺F4/80⁺ macrophages in the WT, HT, and KO HBA of (B) E10.5 (31 to 39 sp) and (C) E11.5 (42 to 48 sp) embryos. Each square represents a single HBA. n = 4; **P < .01; ***P < .001. The percentage of cKit⁺CD41^low progenitor cells in WT, HT, and KO HBA of (D) E10.5 and (E) E11.5 littermates. n = 4; *P = .026; **P = .006. Methylcellulose culture data showing the number of CFU-Cs per 1 ee of E10.5 (F) and E11.5 (G) WT, HT, and KO HBA cells. n = 3; *P = .047. Numbers of each colony type are indicated by bar color. BFU-E, burst forming unit–erythroid; E, erythroid; G, granulocyte; GEMM, granulocyte, erythroid, macrophage, megakaryocyte; GM, granulocyte, macrophage; M, macrophage.