Fig. 4

Masson’s trichrome staining sections of anastomotic tissue on the day3, day7 and day14 after surgery in the three groups (40 ×). Collagen fiber density progressively increased postoperatively in all groups, evolving from thin fibers (day 3) to disorganized proliferation (day 7) and dense arrangement (day 14). No significant intergroup differences in collagen content were found, though the SFB group showed a consistent trend toward higher values at all time points.