Does osteocyte formation cause the nonlinear refilling of osteons?

Marotti (Ital J Anat Embryol 101:25–79, 1996) described a theory of osteocyte differentiation from osteoblasts during bone formation. This theory postulates that, when a previously formed osteocyte is sufficiently covered by new bone and osteoid, it sends an inhibitory signal through its dendritic processes to the neighboring osteoblasts that reduces their individual apposition rates. The osteoblast most affected by this inhibition becomes buried by its neighbors, and becomes one of the next layer of osteocytes. By pursuing this concept, the present study develops a mathematical theory that predicts another observation about bone remodeling: the diminishment of the apposition rate during the refilling of basic multicellular units (BMUs). This decrease in apposition rate is different in osteonal and surface (e.g., trabecular) BMUs, and the theory shows that this result is consistent with the accrual of osteocyte inhibition throughout the refilling period, with the different ratios of bone volume to surface area in these two types of BMUs.