Representative results of in situ hybridization on HIV-1 chronically infected H9 cells (A and B) and MKs infected at day 5 and harvested at day 12 of culture (C and D) using a³⁵S-labeled rev DNA probe. Bright (A and C) and dark (B and D) field images are presented (May-Grünwald staining; original magnification × 1,200 for H9; × 500 for MKs). In day 12 culture, 98% to 99% cells are CD61⁺ megakaryocytic cells with one or more lobes, while ≈ 1% of cells are granulocytes, which are of smaller size (see also Results and Guerriero et al22).