Figure 2.

Critical components of the reversal phase. (a) Cross-section at the starting point of a remodeling unit. The bone marrow envelope is lifted over an osteoclast on initiation of bone remodeling. BME: bone marrow envelope; BLC: bone-lining cell; OC: osteoclast; Rv.C: reversal cell. (b) Three-dimensional reconstruction of a bone resorption site in human iliac crest. The bone surface is shown in yellow, the canopy in semi-transparent purple and the capillary network in blue. OC: osteoclast (red cells on the bone surface). Note the close apposition between capillaries and the canopy. Bone-lining and reversal cells are not shown. Images reproduced with permission.2