TKO bone marrow dies by necrosis. (A) Representative TEM images from Bid^+/+ and TKO mice (top: original magnification ×3200; scale bar, 2 μm; bottom: original magnification ×15 000; scale bar, 500 nm). (B) Quantitation of apoptotic and necrotic cells from Bid^+/+, DKO, and TKO TEM. A total of 100 cells with a nucleus from lower-magnification images were scored based on cell and organelle morphology (see supplemental Methods for quantitation details). (C) TEM images of bone marrow from Bid^+/+ and TKO mice analyzed for membrane bubble. Images of the whole cell are original magnification ×15 000, and zoomed images of the cell membrane are original magnification ×42 000 (scale bars, 500 nm). (D) Quantitation of the number of bubbles show in panel C. (E) Ripk1 fluorescent immunohistochemistry as a marker for necrotic cell death on paraffin-embedded bone marrow sections from Bid^+/+, DKO, and TKO mice. Staining was performed 3 independent times (scale bar, 50 μm). Zoomed-in images (250%) are of the indicated boxed area. (F) Fluorescent immunohistochemistry for cleaved caspase-3 as a marker of apoptotic cell death on Bid^+/+ and TKO bone marrow sections as in panel C. (G) Fluorescent immunohistochemistry for Bid^+/+ liver after tail vein injection with Fas ligand as a positive control for cleaved caspase-3 staining. **P < .01. Data represent mean ± SEM. DAPI, 4′,6-diamidino-2-phenylindole.