Figure 1

Shows images of the tissue reaction to the HA- and the β-TCP-based bone substitutes within goat muscle at given time points of the study (day 28–181). A-C) display the tissue reaction to the HA-based nanocrystalline biomaterial on day 28 (A), day 91 (B) and day 181 (C) after implantation respectively. Note the osteoclast-like giant cells (GC) in close contact with the material (HA) on day 28 and day 91, with no sign of biomaterial breakdown (A: H&E-staining, 100x magnification, scale bar = 10 μm, B: H&E-staining, 200x magnification, scale bar = 10 μm), CT=connective tissue). On day 181 (C) a breakdown of granule integrity by fibrous tissue and phagocytic cells is observed, which resulted in many small particles within the implantation bed (Masson-Goldner-staining, 100x magnification, scale bar = 10 μm). D-F) show the tissue reaction to the β-TCP-based material on day 28 (D), day 91 (E) and day 181 (F). On day 28 the material (TCP) is surrounded and invaded by many multinucleated giant cells (GC) (H&E-staining, 200x magnification, scale bar = 10 μm). On day 91 only few remnants of the biomaterial can be detected, while osteoclast-like giant cells (GC) dominate the implant side. Fragments of the bone substitute are detectable in the cytoplasm of the multinucleated giant cells (dashed line) (H&E-staining, 400x magnification, scale bar = 10 μm. On day 181 fibrous tissue remains after the fast degradation of the biomaterial (H&E-staining, 100x magnification, scale bar = 10 μm).