Immunohistochemical analysis of lymph nodes. Mandibular lymph nodes from two to six mice per group were examined (multiple lymph nodes in some mice). Representative photomicrographs of immunohistochemical staining of lymph nodes from mice from the LT12 group and NT12 group. For the follicular dendritic cell (FDC) network panels, the LT12 lymph node has no FDC networks, but B cells are picked by the CD21 antibody, and the NT12 lymph node has prominent FDC networks. Original magnifications: × 50 (insets), × 400 (CCL19), and × 200 (all other images).