Fig. 4.

Lack of segregated ectopic follicular tissue formation in CXCR5^−/− compared to Wt mice. Paraffin sections with ectopic lymphoid follicles of two representative Wt (a) and sections with loose lymphoid aggregates of two CXCR5^−/− mice (b) 5–17 months after infection were immunohistochemically stained for B (B220 in red) and T (CD3 in blue) cells, for macrophages (F4/80 in red) and B cells (B220 in blue), and for blood vessel formation (CD31 in red, indicated by arrows) and B cells (B220 in blue). Scale bars, 100 μm