Physical and histological differences between severely and mildly compressed spinal cord in tip-toe walking Yoshimura (twy) mice. (A) Representative sagittal T2-weighted images of the severely compressed (S group) and mildly compressed (M group) spinal cords in twy mice (6, 15, and 20 weeks of age). (B) Representative axial T2-weighted images of the S and M groups at 20 weeks of age. Magnetic resonance imaging (MRI) of the S group (A, B) showed clear cervical spinal cord compression resulting from C2/3 ligamentous calcification (*). (C) The canal stenosis ratio of the S group was significantly higher than that of the M group (n = 8 mice per group). ***P <0.001. (D) Body weight in each group (n = 8 mice per group). *P <0.05. (E, F) Motor functional analyses: Latency on the rotating rod and stride length in each group (n = 8 mice per group). *P <0.05. (G) Representative HE-stained axial images of the S and M groups in twy mice. Scale bar: 500 μm. (H) Quantitative analysis of the spinal cord area in the S and M groups (n = 4 mice per group). ***P <0.001.