As it can be seen in many mechanobiological modelings [eg. Claes et al. (1999), Carter et al. (1998), Lacroix and Prendergast (2002), Isakson et al. (2006)], a large amount of fibrous tissue is predicted in the first few iterations in callus but gradually disappears from the healing zone, while, from the clinical point of view, we know that once the fibrous tissue is formed, it neither can be differentiated to any other phenotype nor apoptosis easily.

What happens to this large amount of predicted fibrous tissue and how?