Whereas peripheral T cells can undergo forms of positive selection ( by antigen-driven clonal expansion ) and negative selection ( by abortive stimulation leading to anergy or death ) , neither is exactly the same phenomenon that occurs in the thymic cortex .
whereas peripheral t cells can undergo forms of positive selection ( by antigen-driven clonal expansion ) and negative selection ( by abortive stimulation leading to anergy or death ) , neither is exactly the same phenomenon that occurs in the thymic cortex .
O B-cell_type B-cell_type I-cell_type O O O O B-other_name I-other_name O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-body_part I-body_part O