Peripheral B cells from reconstituted Rag2°IL2Rβ° and Flt3IL7Rα° mice 10 weeks after transplantation with Lin^–cKit⁺Sca1⁺CD45.1⁺ wild-type cells. Age-matched C57Bl/6Ly5.1 mice were used as controls. (A) IgM and IgD profiles on gated CD45.1⁺CD19⁺PI^– splenic cells of the indicated mice. Absolute cell numbers are given in Figure 3B. (B) Peritoneal cavity B1 cells from engrafted mice. Cells were stained for CD45.1, IgM, and CD5. Data represent profiles of CD5 and IgM expression on gated CD45.1⁺IgM⁺PI^– cells. One representative analysis of at least 3 experiments is shown. The dotted line separates the flow cytometric results from the unmanipulated C57Bl/6Ly5.1 from that of the reconstituted recipient mice. Absolute cell numbers are given in Figure 4B.