In vivo macrophage to feces RCT studies. Mice were injected intraperitoneally with [3H]cholesterol-labeled BM-derived macrophages and the amount of radioactivity present in plasma, liver, feces, and adrenals was determined 48 h later. RCT experiments were performed in 3–4-month-old (A) female mice (n = 7) fed a chow diet and (B) male mice (n = 6) fed a 1.25C diet (1.25% cholesterol, 20% fat) for 4 weeks. Data represent mean ± S.E. *, p < 0.05; †, p < 0.01; ‡, p < 0.001.