SIV-associated lymphomas. Sections were stained with hematoxylin and eosin (A, B, and C), immunostained with anti-CD3 MoAb (D) and anti-CD20 MoAb (E, F), and hybridized with the SG5 SIV gag oligoprobe (G, H, I). Monkey S1 (A, D, and G) is a peripheral CD3⁺ T-cell lymphoma (D); CD3⁺ cells (yellow) show a positive in situ hybridization signal (brown) (G). Monkey 8503 (B, E, and H) is a centroblastic CD20⁺ B-cell lymphoma (E) showing a negative in situ hybridization signal (H). Monkey OD5 (C, F, and I) is a centroblastic CD20⁺ B-cell lymphoma (F) showing a positive in situ hybridization signal (I).