Thymus microenvironments in BMT mice. (A and B) Confocal analysis of frozen thymus sections from untreated and post-BMT mice at the indicated time points are shown, labeled with CD205 and ERTR5 to identify cortex and medulla (A) and ERTR5 and Aire to detect Aire⁺ mTECs (B). Dashed/dotted lines denote corticomedullary junction. Scale bars denote 200 μm (A) and 50 μm (B). C, cortex; M, medulla.