Impaired intervertebral disk maturation and spontaneous degeneration in mice with conditional deletion of FOXO. (a) Safranin O staining in lumbar intervertebral disk (IVD) samples isolated from Col2a1Cre−/− and Col2a1Cre‐FOXO KO mice at 1, 2, 4, and 6 months of age (n = 6–8 mice per group). NP: nucleus pulposus; AF: annulus fibrosus; EP: endplate. Magnification bar = 100 µm. (b) Histopathological scores in the nucleus NP/AF and EP of lumbar IVD samples isolated from Col2a1Cre−/− and Col2a1Cre‐FOXO KO mice at 1, 2, 4, and 6 months of age (n = 6–8 mice per group). (c) Measurement of disk height of lumbar IVD samples from Col2a1Cre−/− and Col2a1Cre‐FOXO KO mice at 1, 2, 4, and 6 months of age (n = 6–8 mice per group). (d) Quantification of cellularity in the NP, AF, and EP of lumbar IVD samples isolated from Col2a1Cre−/− and Col2a1Cre‐FOXO KO at 1, 2, 4, and 6 months of age (n = 6–8 mice per group). (e) Photograph (left) and µ‐CT image (right) of 6‐month‐old Col2a1Cre−/− and Col2a1Cre‐FOXO TKO mice. Values shown are mean ± SD. Statistical comparisons were assessed by one‐way analysis of variance (ANOVA) followed by a post hoc Tukey's test. *p < 0.05