Fig. 3

a1 Hematoxylin-eosin(HE) staining of the lumbar facet joint in the normal group showed that that the cartilage and subchondral bone boundary were clear and the chondrocyte arrangement rules (a: NG, normal group). a2 Immunohistochemistry of the lumbar facet joint in the normal group showed strong positive staining in the subchondral bone area, whereas the cartilage area showed negative staining. a3 PBS, instead of a primary antibody, was used as a negative control in the immunohistochemical analysis. b1 HE staining of the lumbar facet joint in the degeneration group showed that the cartilage and the subchondral bone area had blurred boundaries and irregular chondrocyte arrangement. (b: DG, degenerative group). b2 Immunohistochemistry of the lumbar facet joint in the degeneration group showed that the subchondral bone area stained positive, and the cartilage area stained negative. b3 PBS, instead of a primary antibody, was used as a negative control in the immunohistochemistry. c1 HE staining of the lumbar facet joint in the severe degeneration group showed that chondrocytes extended through the cartilage line and that chondrocytes were reduced in number and disordered (c: SDG, severe degeneration group). c2 Immunohistochemistry of the lumbar facet joint in the severe degeneration group showed that the subchondral bone area staining was weakly positive, whereas the staining of the cartilage area was negative. c3 PBS, instead of a primary antibody, was used as a negative control in the immunohistochemical analysis