Figure 2.

Hematoxylin & Eosin staining of tissue sections from EL-4-derived tumors. Panels A and B show low and high magnification (with scale bars) of a typical EL-4 tumor from a mouse mock-vaccinated with PBS three weeks before challenge. Panels C and D show low and high magnification (with scale bars) of EL-4 tumor sections from a mouse vaccinated with RAG × EL-4 semi-allogeneic hybrids three weeks before challenge. Note, that both tumors appear to be poorly differentiated (anaplastic), and that there are no morphologic features that distinguish them.