Contribution of α4 integrin^–/– and wild-type embryonic cells to lymphohematopoietic tissues. (A) The level of reconstitution in the peripheral blood of recipient mice is maintained over time, up to 500 days after transplantation. Each symbol and connecting line represents an individual mouse that has been reconstituted with α4 integrin^–/– E12.5 fetal liver (n = 5), yolk sac (n = 2), AGM region (n = 1), or peripheral blood (n = 4). (B) Mice that received transplants of α4 integrin^–/– () or wild-type (▪) E12.5 embryonic tissues (fetal liver, AGM region, yolk sac, and peripheral blood) were analyzed for donor contribution in various tissues using flow cytometry. Note the deficiency in colonization of the peritoneal cavity and the Peyer patches with α4 integrin^–/– cells. The mean for relative contribution, as compared to the percent reconstitution in peripheral blood, is plotted. Bars represent standard error (*P < .01; wild-type n = 7, α4 integrin^–/– n = 7).