Histologic examination of enlarged lymph nodes from Roquin^san/+ mice. Sections from enlarged (A-F) or nonenlarged lymph nodes (G-H) were stained with hematoxylin and eosin (A,G-H) or antibodies to the macrophage marker F4/80 (B), B-cell marker pax-5 (C-D), or pan-T-cell marker CD3ϵ (E-F). Sections are representative of 19 mice analyzed. All mice are 26 to 40 weeks of age.