Figure 1.

Origin of Thymic B cells. Schematic representation of different pathways involved in the origin of thymic B cells. One pathway proposes intrathymic differentiation from fetal liver and bone marrow B cell progenitors that give rise to resident thymic B cells. A second pathway is the migration of mature B cells, which acquire the phenotype of resident thymic B cells through the interaction with developing thymocytes (discussed in Section 2).