Abnormal TEC organization and TEC apoptosis following inactivation of host-type pAPCs. (A) Lack of a regular TEC organization in the BM chimeras described in Figure 5, as demonstrated by altered intracellular expression of K5 and K18²⁵  at 2 weeks. (B) For analysis of apoptotic TECs, thymic sections were stained as in Figure 1. Colocalization of TUNEL and K18 depicts apoptotic TEC (arrows in panel iii). Four individual experiments were performed, with 2 to 4 animals per group and experiment. These experiments yielded comparable results, and therefore a representative photomicrograph of one mouse for each group is shown.