Final answer:
Plasma cells, which are terminally differentiated B cells, leave the secondary lymphoid organs and migrate back to the bone marrow after secreting antibodies for a specific period.
Step-by-step explanation:
After B cells are activated by their binding to antigen, they differentiate into plasma cells. Plasma cells often leave the secondary lymphoid organs and migrate back to the bone marrow, where the whole differentiation process started. After secreting antibodies for a specific period, they die, as most of their energy is devoted to making antibodies and not to maintaining themselves. Thus, plasma cells are said to be terminally differentiated.