Structural changes in inguinal PLN volume, HEV network, and B-cell follicle size and distribution during LCMV infection. (A) Representative OPT images of B220⁺ areas (green) and HEVs (red) showing an initial increase in the B-cell follicle size on day (D2) after infection followed by incremental loss of regular follicle organization by day 8 after infection (D8). Arrows indicate superlarge follicles (> 25 × 10⁶ μm³); asterisks, small B-cell clusters (< 5 × 10⁶ μm³). Scale bar = 400 μm. (B top) Absolute volume, B-cell volume, and HEV length of inguinal PLN during LCMV infection. Each dot represents 1 PLN. (Bottom) Fold-increase compared with day 0. Data are shown as mean ± SEM *P < .05, ***P < .001, n.s., not significant (1-way ANOVA). (C) Change in B-cell follicle size distribution during LCMV infection. B-cell follicle sizes were classified as in Figure 2C. Pooled from a total of 6 to 12 inguinal, popliteal, and axillary PLNs from 3 to 7 mice for each time point.