Abstract
Peripheral lymphoid tissues, such as lymph nodes and Peyer's patches (PPs), are organs required for mounting highly efficient immune responses to small quantities of Ag. The compartmentalization of the cellular components involved in the immune response into distinct zones supports the function of these tissues; however, little is known about how this compartmentalization is achieved. In this study, we analyzed neonatal PP development and present evidence that the CD3(-)IL-7Rα(+) PP inducer cells that initially play a pivotal role in the formation of the PP anlagen are involved in the formation of B and T cell zones in neonatal mice. PP inducer cells migrate between these zones by undergoing chemokine receptor switching.