Analysis of intervertebral disk (IVD) size in embryonic day (E) 17.5 embryo thoracic spine and 4-week–old tail in JNK1/2 dKO and control (CTRL) mice. Dot plots for comparisons of IVD components between E17.5 CTRL and dKO mice. IVD measurements were taken at the level of two thoracic IVD: T10 to T11 and T11 to T12 in E17.5 dKO and CTRL mice. A–C: An average (AVG) of the two segments was reported for vertebral growth plate (GP) length (A), ventral annulus fibrosus (AF) width (B), and nucleus pulposus (NP) width (C). D–F: Dot plots for comparisons of proximal tail IVD measurements between 4-week–old wild-type (WT), CTRL, and dKO mice, showing IVD width (D), NP height (E), and NP width (F). Data are expressed as means ± SEM (A–F). n = 6 (A–F, CTRL); n = 3 (A–F, dKO); n = 4 (D–F, WT). ∗P ≤ 0.05, ∗∗P < 0.01.