FIGURE 1.

Ablation of embryonic Col2+ progenitors in mice causes absence of the spine. A, Gross appearance of Col2‐cre, and Col2‐cre;DTA^fl/− mice at P0. B, X‐ray images for P0 Col2‐cre, and Col2‐cre;DTA^fl/− mice. Yellow arrow: spine is completely absent in mutant newborn compared to Col2‐cre control. C, Alizarin red and Alcian blue staining of newborn Col2‐cre and Col2‐cre;DTA^fl/− mouse. Yellow arrow: spine complete loss in mutant newborn. Scale bar = 1 mm. D, The tail of Col2‐cre and Col2‐cre;DTA^fl/− newborns mice stained by Goldner's trichrome. Scale bar = 300 μm. E,F, Higher magnification of Golden staining in tail vertebra and skin. Yellow arrow: vertebral and intervertebral disc (IVD) complete loss in mutant newborn. Six mice evaluated in each group. Scale bar = 100 μm