Histology observation of laminectomy site in FAM (a), CAM (b), non-treatment (c), and AFF groups (d) by H&E staining at 12 weeks postoperatively (×100; CAM cross-linked amniotic membrane, FAM freeze–dried amniotic membrane, EF epidural fibrosis, DM dura mater, NC neural cord, FT fat tissue, NB newly formed bone)