Figure 3. Graph depicting the expression of genes in the dental follicle of the rat 1st mandibular molar at various days post-natally. At day 3, the major burst of osteoclastogenesis, osteoprotegerin is down-regulated such that a favorable RANK/osteoprotegerin ratio is established to promote osteoclastogenesis. At this time, CSF-1 is maximally expressed, both to down-regulate osteoprotegerin expression and to promote osteoclast precursor recruitment and osteoclastogenesis. At day 10, the minor burst of osteoclastogenesis, VEGF is maximally expressed to stimulate RANK expression on osteoclast precursors, as well as to interact with RANKL and CSF-1 to promote osteoclastogenesis. At this time, RANKL is up-regulated such that a favorable RANKL/osteoprotegerin ratio could exist to stimulate this minor burst of osteoclastogenesis.