Gross and microscopic morphology of LMP1-expressing and nonexpressing BL tumors. Female BALB/c nu/nu mice were injected subcutaneously with 1 × 107 cells from exponentially growing BL41 EBV− cell line (A, B, and C); EBV-P3HR-1–converted BL41 cell line (D, E, and F); EBV-B95-8–converted BL41 cell line (G, H, and I); or LMP1-transfected (J, K, and L) BL41 cell line. Tumors were removed in toto 8 to 14 weeks after the initial inoculation and processed for histology. (A, D, G, and J) Gross morphology of Burkitt's tumors removed in toto with abstract epidermis and dermis showing in (A) and (D) mostly viable-looking tumor tissue with small areas of central necrosis, and in (G) and (J) tumors with extensive necrosis and little viable tumor (no magnification). (B, E, H, and K) Microscopic morphology (original magnification × 10) of Burkitt's tumors showing in (B) and (E) viable-looking tumor tissue, and in (H) and (I) the abrupt interface between necrotic and viable tumor tissue. (C, F, I, and L) Higher power magnification (original magnification × 40) of viable tumor tissue with patent capillaries containing red blood cells (C) and (F), and capillaries occluded with thrombi at various stages of organization (I and L).
