“…Different stages in giant cell evolution from formation to degeneration have been described, but little is understood about either the composition or behaviour of the non-giant cell elements that form the bulk of PGCG (Sapp, 1972;Katsikeris et d , 1988;Dayan et ~i l , 1990). Mineralised tissue, (principally woven and lamellar bone, and less often dystrophic calcification), occurs within !4-54% of PGCG indicating that osteoblasts are present, and while osteoblasts influence the behaviour of osteoclasts, it is unknown if this effect extends to PGCG giant cells (Brown et al, 1956;Giansanti and Waldron, 1969;Bhaskar ef al, 1971;Macleod and Soames, 1987;Katsikeris et al, 1988;Dayan et af, 1990;Rodan, 1992;Raisz et al, 1993). Myofibroblasts, and either macrophages, or their precursors are present (Regezi et al, 1987;Dayan et al, 1989).…”