Figure 1.

Remodeling unit in human iliac crest biopsy. Remodeling progresses to the left, as indicated by the time axis drawn relative to the bone surface. Histomorphometry indicates that a period of several weeks separates bone-resorbing osteoclasts from bone-forming osteoblasts (cells on osteoid beneath the blue line).10 This period is called reversal phase (demarcated by the dotted black lines). Mineralized matrix: blue; osteoid: red. Note the canopy of elongated cells (blue arrowhead) covering the bone-remodeling site. Image reproduced with permission.11