The spleen and other peripheral organs are not required for the maturation of B cells in the bone marrow. (A) B-cell maturation proceeds normally in the bone marrow in splenectomized LTα-deficient mice (lacking all secondary lymphoid organs). Bone marrow B cells were analyzed for AA4.1 expression 2 and 15 days after splenectomy. Recently generated AA4.1^hi B-cell populations were observed after splenectomy and were comparable to those in nonsplenectomized LTα⁺ mice, although overall B-cell production was enhanced after splenectomy. A representative experiment is shown; n = 3 mice in each group. (B) B-cell maturation proceeds normally in the bone marrow in splenectomized aly/aly mice. Bone marrow B cells of aly/aly mice were analyzed for AA4.1 expression 30 days after splenectomy. Recently generated AA 4.1^hi B-cell populations were observed in these mice even after splenectomy and are comparable to those in aly/+ mice. A representative experiment is shown; n = 3 mice per group.