The expression of VpreB3 (brown) in human hematopoietic and lymphoid tissues. Bone marrow biopsies (A) showing, scattered VpreB3 positive lymphoid cells (hematoxylin counterstain for nuclei, 400x), and (inset) partial co-localization of VpreB3 with the lymphoid immaturity marker TdT (dark blue nuclear, no hematoxylin counterstain, 1000x). Reactive tonsil (B) showing VpreB3 staining in a subset of lymphoid cells concentrated within germinal centers (hematoxylin counterstain, 100x, inset 1000x). Spleen (C) showing VpreB3 staining in a subset of lymphoid cells within the white pulp (hematoxylin counterstain, 100x). Tonsil (D-I) co-stained for VpreB3 (brown) and (D) CD10, (E) BCL6, (F) HGAL, (G) LMO2, (H) MUM1/IRF4, and (I) BLIMP1 (blue stains, no hematoxylin counter-stain, D and G at 1000x; E, F, H and I at 200x).