Osx-Cre targets cells in the CEP of IVD tissues at postnatal stages. (a, b) Fluorescence images of EGFP/mTomato on intervertebral disc sections from 2-week-old (a) and 2-month-old (b) Osx-Cre; R26-mTmG mice. (c–h) Higher magnification EGFP/mTomato images for AF (c,d), CEP/GP (e,f), and NP (g,h) from 2-week-old (c,e,g) and 2-month-old (d,f,h) Osx-Cre; R26-mTmG mice. Red: membrane-targeted tdTomato; Green: membrane-targeted EGFP. CEP: cartilaginous endplate; GP: growth plate cartilage; NP: nucleus pulposus; IAF: inner annulus fibrosus; OAF: outer annulus fibrosus. Images shown were representative results from three independent mice analyzed [Color figure can be viewed at wileyonlinelibrary.com]