Fig. 1.

The cutting cone. The cutting cone originates in close proximity to neurovascular axial bundles and is generated by the propagation of the basic multicellular unit (BMU). The cutting cone consists of a set of osteoclasts, followed by a set of osteoblasts, reversal cells and secondary osteoclasts that cover the so-called reversal zone. At the end of the reversal zone, a set of osteocytes generate the closing zone. A line of symmetry divides in half the representation of a complete BMU in the cortex moving toward the longitudinal axis of the long bone. One-half of cortical BMU is similar to the BMU at the cancellous surface, although in cancellous bone, the BMU is separated from the marrow by a specific cell structure called the canopy