Fig. 4

Histological analysis using picrosirius red staining and polarized light microscopy to assess the healing outcome at 1 month after surgery. In the tendon ECM scaffold group, a distinctly wavy and more aligned ECM structure was observed, characterized by a pronounced birefringence. Furthermore, a more abundant presence of thicker collagen fibers was observed compared to both the suture repair and ADM-mediated repair groups. However, the fiber thickness in the tendon ECM scaffold group remained lower than that observed in the healthy tendon group, suggesting an ongoing regenerative stage at the 1-month time point