Comparison of BM and splenic B cell differentiation. The cells in the BM or spleen were assessed with each surface marker. The representative FACS plots are demonstrated by FlowJo. (A) The results of BM are indicated for B cell differentiation stages of pro-B, pre-B, immature B (IMB), and mature B (MB) cells. The histograms indicate the means and SD of the 6 littermates with same gender pairs for these cell stages. No statistical significant difference between Sfrp2+/+ and Sfrp2-/- in these cell stages was observed by Student’s t-tests. (B) The results of splenic B cells for transitional type 1 (T1), marginal zone B (MZB), transitional type 2 (T2), and follicular B (FOB) cells are indicated. The histograms indicate the means and SD of the 6 gender-matched littermates. In splenic B cells, there was no statistical significant difference between Sfrp2+/+ and Sfrp2-/- by Student’s t-tests.