TBMs originate from LN-resident precursors. (A) Scheme of chimeric mouse production. (B and C) Immunofluorescence staining of brachial LNs and PPs of fully irradiated chimeric mice. (D and E) Immunofluorescence staining of brachial LNs and PPs derived from shielded chimeric mice. (F) Quantification of CD68⁺ GFP⁺ to CD68⁺ cells ratios. Each dot represents the ratio in a single GC. Four mice were analyzed in two independent experiments. Line represents the mean. ****, P < 0.0001; ns, not significant; two-tailed Student’s t test.