Fig. 4
A. AFM was used to observe the microstructure of AF and NP collagen fibers. The representative AFM images of collagen fibrils in AF and NP of the control group and the experimental group after bearing immobilization for 2, 4, 6 and 8 weeks, respectively. The top row represents the AFM image of the NP (a-e), and the image in the lower row represents the AF AFM image (f-j). AFM indicates Atomic force microscopy; AF indicates annulus fibrosus; NP indicates nucleus pulposus. B. The average elastic modulus of collagen fibrils with different immobilization duration. a).The elastic modulus of NP were analyzed. b).The elastic modulus of AF were analyzed. (*) indicates significant difference from other groups discs (p ≤ 0.05), (+)indicates significant difference from other groups (p ≤ 0.001)