Figure 4: Representative Masson staining micrographs of bone at site of defect after 4 weeks ((a)–(c)) and 12 weeks ((d)–(f)) of implantation: untreated group ((a), (d)), gelatin group ((b), (e)), and gelatin/β-TCP group ((c), (f)). Black arrows denote the boundary between nascent bone and host bone. M, material; HB, host bone; NB, nascent bone; MC, medullary cavity; FV, fat vacuoles; and FT, fibrous tissue. Scale bar: 100 μm.