Fig. 4

The results of histological evaluation for tendon repair at 4 weeks after surgery. a The HE staining of window defect on the patellar tendon at 4 weeks after surgery. b Masson’s trichrome staining of window defect on the patellar tendon at 4 weeks after surgery. c Fiber alignment score was significantly higher for the rats in the BMSC-EVs and fibrin groups compared with control group (n = 8 donors). Bars: 100 μm, ×20. Data are represented as mean ± SD. **p < 0.01