Fig 1: Lymphoma growth disrupts CCL21 migration cues on FRCs(A) Microscopic analysis of the FRC network (Ccl19RFP) in LN sections. Bottom: examples of FRC sphericity (Ccl19RFP segmentation).(B) Quantification of the FRC density in LN sections of Ccl19RFP mice. n = 7–10 mice per group.(C) Representative images of CCL21 expression in LNs sections of Ccl19RFP mice and gradients of the fluorescence intensity over the distance.(D) CCL21 distribution around and within HEVs (PNAd+) and FRCs (Ccl19RFP).(E) Microscopic analysis of CCL21 (MFI) within masked Ccl19RFP (FRCs) and PNAd+ (HEVs). Control n = 5, tumor n = 7.(F) Immunohistochemistry of CCL21 expression in controls and LNs from diseased tg. Eµ-Myc (n = 7) and Cd19-TAg mice (n = 11); box indicates magnified area. Bar graph depicts percentage of LNs with preserved (pos.) or lost (neg.) CCL21 expression.(G) Proportions of mesenchymal cell subsets (all Ccl19RFP), CD21/CD35+ follicular DCs (FDCs); MadCAM-1+ marginal reticular cells (MRCs); SCA-1+ pericytic reticular cells (PRCs); and T-zone reticular cells (TRCs). n = 4 mice per group.(H and I) FCM quantification of CCL21+ (n = 6–7 mice per group) (H) and PDPN+ expression (n = 7–8 mice per group) (I) in LNs of Ccl19RFP mice.(J and K) Exemplary images (J) and analysis (K) of aSMA (MFI) and CCL21 (integrated density) in a FRC line cultured under static conditions or with laminar flow.Scale bars, 20 µm (A, D, and J) and 100 µm (C and F). Mean and SEM are indicated. Data points represent individual cells (K) or mice (B, E, and G–I). A Mann-Whitney U-test was applied. *p < 0.05; **p < 0.01; ***p < 0.005.