Immunohistochemistry with different monoclonal antibody fragments reveals EDB and EDA expression in B-cell lymphoma xenografts. Immunohistochemical stainings using the antibodies L19, specific to EDB fibronectin (Fn-EDB), and F8, specific to EDA (Fn-EDA), both well-established markers of neovascular structures in solid tumors, revealed a strong expression of these fibronectin isoforms with a prominent vascular pattern of staining in Ramos lymphoma xenografts (left panel). The staining is similar to the staining pattern of L19 and F8 in solid tumors, as exemplified with the U87 glioblastoma xenograft (right panel). In contrast, Ramos lymphomas were consistently negative for the large isoforms of tenascin C (using the antibody F16, specific to the domain A1 of human tenascin C, TnC-A1), whereas the glioblastoma displayed a positive staining in the same experiment. For negative controls, the primary antibody was omitted. Scale bars, 100 μm.