Distribution of α4 integrin^–/– and wild-type donor cell subsets in recipient tissues. Adult hematopoietic tissues of mice reconstituted with E12.5 embryonic tissues (AGM region, yolk sac, peripheral circulation, and fetal liver) of wild-type and α4 integrin^–/– origin were analyzed by flow cytometry, and sample plots are given (see Table 2 for corresponding statistics. (A-C) Lymphoid (B220⁺ B-cell and CD3ϵ⁺ T-cell) and myeloid (CD11b/Gr1) populations for wild-type and α4 integrin^–/– donor fractions of the peripheral blood (A), BM (B), and spleen (C) are illustrated. Mature B220⁺IgD⁺ and CD19⁺IgM⁺ B cells were produced by α4 integrin^–/– HSCs in BM and spleen (B, C). Early α4 integrin^–/– B cells expressing AA4.1 enter the spleen normally (C). (D,E) CD4/CD8α staining in the thymus (D) and lymph nodes (E) indicates normal T-cell development and distribution in α4 integrin^–/– donor populations, as compared to wild-type T cells. (F,G) The inability of α4 integrin^–/– cells to engraft the Peyer patches or peritoneal cavity is particularly apparent in the B-cell populations of these tissues. This is most noticeable in the mature B220⁺IgM⁺ population of the Peyer patches (F) and the B220⁺CD5⁺ B-1 cells of the peritoneal cavity (G).