FIG. 4.

Histological observation of the TM healing after grafting. In the SFS group, prominent hyperplasia was evident in the epithelial and connective tissue (CT) layers and at the perforation edge on days 3 and 5, with minor inflammatory responses seen throughout the healing process. In the ACS group, epithelial hyperplasia and vascular proliferation were evident in the early stages (day 3–7). Infiltrating cells resembling fibroblasts were abundant in the CT layer with a few lymphocytes surrounding the implant. The perforations in SFS and ACS groups closed early at 7 days, and the structure of healed TMs appeared normal at 28 days. Paper patch elicited lymphocytic cell infiltration with prominent exudates at 9–28 days. Gelfoam also induced the infiltration of inflammatory cells, and fibroblast proliferation was prominent in the CT layer. The perforations in paper and Gelfoam groups closed on days 7 and 9, respectively, with atypical and thickened healed TMs at 28 days (white arrows). In the control group, TM healing was relatively slower compared with scaffold-treated groups. The perforation remained patient in the first week, and a keratin spur was seen on day 5. The perforation had closed at 9 days with significant thickening throughout the three TM layers. By 28 days, the healed TM became thinner with residual thickening at the previous perforation site (white arrow). Black arrowheads indicate TMs; black arrows indicate scaffolds. EAC, external auditory canal; ME, middle ear; m, handle of malleus; spur, keratin spur. Haematoxylin and eosin (H&E) staining. Scale bars: 200 μm.