Fig. 3.

B cell development in FL and FBM. a. Schematic representation of proposed fetal B cell maturation according to immunophenotypic markers and stages of VDJ recombination (using human fetal B cell development data where available) [5], [6], [29] that was studied in 2nd trimester FL and FBM. b. Representative flow-cytometric analysis of FL and FBM of the same fetus (GA 17 weeks) showing the gating strategy used to identify the various stages of B cell maturation as described in (a). Data are from viable CD34 negative cells for the FL sample and viable mononuclear cells for the FBM sample. c. Frequencies of the B cell stages, expressed as % of CD34-CD19 + cells, are shown in the bar graph with data represented as mean ± SEM from FL (n = 13) and FBM (n = 12) samples. (Imm: immature, Trans: transitional, Mem: memory B-cells; *p < 0.05, **p < 0.01).