Defects in early B cell development in Mki67 ^−/− mice are rescued by pre-rearranged H and L chains. (A) Gating strategy of pre-pro-B, large pre-B, and small pre-B cells when a pre-rearranged H chain was present in the WT- (Rag1^−/−SW_HEL-HC^Ki/Ki) or Mki67^−/−-Rag1–deficient (Mki67^−/−Rag1^−/−SW_HEL-HC^Ki/Ki) condition. Representative percentages of the gated populations of the parental gate are shown. (B) Quantification of cell numbers of pre-pro-B, large pre-B, and small pre-B cells per femur in WT- (n = 3) or Mki67^−/−- (n = 5) Rag1^−/−SW_HEL-HC^Ki/Ki mice. (C) Gating strategy of pre-pro-B and immature B cells when both pre-rearranged H and L chains were present in the WT- (Rag1^−/−SW_HEL-HC^Ki/KiLC^Tg/+) or Mki67^−/−-Rag1^−/− (Mki67^−/−Rag1^−/−SW_HEL-HC^Ki/KiLC^Tg/+) conditions. Representative percentages of the gated populations of the parental gate are shown. (D) Quantification of cell numbers of pre-pro-B and immature B cells per femur in WT- (n = 5) or Mki67^−/−- (n = 4) Rag1^−/−SW_HEL-HC^Ki/KiLC^Tg/+ mice. (E) Quantification of cell numbers of CD19⁺ B cells per spleen in WT- (n = 5) or Mki67^−/−- (n = 4) Rag1^−/−SW_HEL-HC^Ki/KiLC^Tg/+ mice. All data are representative of two independent experiments. Statistical differences were determined in B by multiple unpaired t tests (corrected for multiple comparisons using the Holm–Sidak method) and in D and E by two-tailed unpaired t test. P values or adjusted P values are shown. ns, P > 0.05.