Erythroid responses to PHZ challenge in Spi-C–deficient and VCAM-1–deficient mice. (A) Cellularity and total number of Ebs in the femur (left panels) and spleen (right panels) of respective controls for each group of mice (red bars), Spi-C–deficient mice (blue bars, upper panels), VCAM-1–deficient mice (peach bars, middle panels), and control mice irradiated and transplanted with either control donor cells (red striped bars) or VCAM-1–deficient donor cells (peach striped bars, lower panel). (B) Erythroid maturation profiles in femur and spleen of Spi-C–deficient mice (blue lines, left panels) VCAM-1–deficient mice (peach lines, middle panels) and control mice irradiated and transplanted (Tx) with either control donor cells or VCAM-1–deficient donor cells (peach lines, right panels) and their respective controls (red lines) at day 4 (solid lines) and at day 6 post-PHZ (broken blue, peach, and red lines, respectively). Blue bars and lines, n = 3 for each time point; and peach bars and lines, n = 3 to 5 mice for each time point; red bars and lines, n = 6 to 12 mice for each time point. Significant difference over controls; *P < .05 d, day; Baso, basophilic Eb; Poly, polychromatophilic Eb; Ortho, orthochromatic Eb; Pro, proerythroblast.