CD163+ macrophage distribution in soleus muscles. A, C, E, G: Wild-type muscles. B, D, F, H: IL-10 null mutant muscles. A, B: Ambulatory control muscles showing CD163+ macrophages (arrows) in the endomysium surrounding muscles. C, D: In muscles experiencing unloading only, the numbers and distribution of CD163+ macrophages did not differ from ambulatory controls and fibers are atrophied. E, F: At 1-day of muscle reloading, both wild-type and IL-10 null muscles show numbers of CD163+ macrophages that are similar to ambulatory controls. G, H: At 4-days of reloading, CD163+ macrophage numbers have increased substantially in wild-type muscle, but show little increase in IL-10-null muscles. All images are at the same magnification; bar = 100 μm.